examples of in text citations in a research paper

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• When neither the author nor the page number is mentioned in the body of the sentence, you should include both the author’s last name and the page number in the parenthetical citation.

Colleges and universities need to create policies that foster inclusion for low-income students (Jack 24).

• When the author’s name is mentioned in the sentence, you should include only the page number in your parenthetical citation.

As Anthony Jack argues, colleges and universities need to create policies that foster inclusion for low-income students (24).

• If the source you are writing about does not have page numbers, or if you consulted an e-book version of the source, you should include only the author’s name in the parenthetical citation:

Colleges and universities need to create policies that foster inclusion for low-income students (Jack).

• If you mention the author in the body of the sentence and there is no page number in the source, you should not include a parenthetical citation.

As Anthony Jack argues, colleges and universities need to create policies that foster inclusion for low-income students.

• If you are referring to an entire work rather than a specific page, you do not need to include a page number.

In The Privileged Poor, Anthony Jack describes many obstacles that low-income students face at selective colleges and universities.

• If you are referring to a source that has no listed author, you should include the title (or a shortened version of the title) in your parenthetical citation.

Harvard College promises “to educate the citizens and citizen-leaders for our society” (“Mission, Vision, & History”).

• If you are referring to a source that has two authors, you should include both authors in your parenthetical citation.

The researchers tested whether an intervention during the first year of college could improve student well-being (Walton and Cohen 1448).

• If you refer to a source that has more than two authors, you should include the first author’s name followed by et al. ( Et al. is an abbreviation for et alia which means “and others” in Latin.) When you use et al. in a citation, you should not put it in italics.

The researchers studied more than 12,000 students who were interested in STEM fields (LaCosse et al. 8).

• If you refer to more than one source by the same author in your paper, you should include the title (or a shortened version of the title) in your parenthetical citation so that readers will know which source to look for in your Works Cited list. If you mention the author’s name in the sentence, you only need to include the title and page number. If you mention the author and title in the sentence, you only need to include the page number.

Colleges and universities need to create policies that foster inclusion for low-income students (Jack, Privileged Poor 24).

According to Anthony Jack, colleges and universities need to create policies that foster inclusion for low-income students ( Privileged Poor 24).

As Anthony Jack writes in Privileged Poor, colleges and universities need to create policies that foster inclusion for low-income students (24).

• If you want to credit multiple authors for making the same point, you can include them all in one parenthetical citation. 

Students who possess cultural capital, measured by proxies like involvement in literature, art, and classical music, tend to perform better in school (Bourdieu and Passeron; Dumais; Orr).

• If you refer to a source that includes line numbers in the margins, numbered paragraphs, numbered chapters, or numbered sections rather than page numbers, you should include the number in your parenthetical citation, along with “line,” “ch./ chs.,” or “sec./secs.”   You can include stable numbering like chapters even when there are no stable page numbers (as in an e-book). You should separate “line” or other designation from the work’s title or author’s name with a comma.  If the source does not include this type of numbering, you should not include it either.

We learn that when he went to the store to buy clothes for his son, “a frantic inspection of the boys’ department revealed no suits to fit the new-born Button” (Fitzgerald, ch.2).

• If you are citing a play, you should include the act and scene along with line numbers (for verse) or page numbers, followed by act and scene, (for prose).

Guildenstern tells Hamlet that “there has been much throwing about of brains” (Shakespeare, 2.2. 381-382).

Chris is in this mindset when he says, “a couple minutes, and your whole life changes, that’s it. It’s gone” (Nottage, 13; act 1, scene1).

• If you are referring to a video or audio recording that contains time stamps, you should include the time in your parenthetical citation to make it easy for your readers to find the part of the recording that you are citing.

In the Stranger Things official trailer, the audience knows that something unusual is going to happen from the moment the boys get on their bicycles to ride off into the night (0:16).

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APA in-text citations

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In-text citations are a brief version of citations that are used to provide information about the sources being referred to by the author. They are used in the text to indicate to the reader that complete information of the citations referred to is available in the reference list, which will enable the reader to locate or access the sources being cited. To provide in-text citations, you must have the following two important elements:

Name of the author or organization

Publication year

Types of in-text citations

APA citation follows the author–date system. Two types of in-text citations are used in APA style. However, it is not necessary to follow the same type of citation throughout the paper. You must choose the appropriate type depending upon how you construct your sentence. There are two types of in-text citations:

Narrative citations

Parenthetical citations

Narrative citation

This type of citation is used when the name of the author or the organization and the year of publication are incorporated into the text and act as a part of the sentence. See the below examples:

With the author

Sivasankar (2007) argues that education for women is important to develop a nation.

Organization functioning as the author

IPIECA (2007) released the oil and natural gas industry guidelines.

Notice that only the publication year is enclosed in parenthesis for narrative citations.

Parenthetical citation

Parenthetical citations are used when both the name of the author or the organization and the year of publication appear inside parenthesis. In parenthetical citations, a comma separates the author from the publication year.

It is argued that education for women is important to develop a nation (Sivasankar, 2007).

It was concluded to release the oil and natural gas industry guidelines (IPIECA, 2007).

If you want to add any additional information in a parenthetical citation, provide the information after the year with a comma as a separator. Phrases or words such as “for more information, see,” “see,” and “e.g.,” can also be used in parenthetical citations. These are illustrated in the below examples:

With author

It is argued that education for women is important to develop a nation (Sivasankar, 2007, p. 7).

It is argued that education for women is important to develop a nation (see Sivasankar, 2007, p. 7).

However, when a citation appears along with some text in parenthesis, use a semicolon as a separator.

It is argued that education for women is important to develop a nation (e.g., the significance of Indian women; Sivasankar, 2007, p. 7).

Examples of in-text citations:

Narrative: Author Surname (Publication Year)

Parenthetical: (Author Surname, Publication Year)

Narrative: Hannula (2006)

Parenthetical: (Hannula, 2006)

Two authors

The surnames of the first author and the second author are separated by “and” in narrative citations. However, use an ampersand symbol in parenthetical citations.

Narrative: Author Surname1 and Author Surname2 (Publication Year)

Parenthetical: (Author Surname1 & Author Surname2, Publication Year)

Narrative: Kleanthous and Williams (2013)

Parenthetical: (Kleanthous & Williams, 2013)

Three or more authors

If the number of authors is three or more, use the first author’s surname followed by “et al.” in both narrative and parenthetical citations.

Narrative: Author Surname1 et al. (Publication Year)

Parenthetical: (Author Surname et al., Publication Year)

Narrative: Towers et al. (2018)

Parenthetical: (Towers et al., 2018)

Group author

If the reference has a group author, use it in place of the author’s name. The group author can be abbreviated. Note that there is a difference in using the abbreviation between a narrative and a parenthetical citation.

If the first occurrence appears in a narrative citation, include the abbreviation along with the year in parenthesis. If the first occurrence appears in a parenthetical citation, you need to include the abbreviation inside square brackets, as the citation is already inside parenthesis.

Narrative: Group author (Abbreviation, Publication Year)

Parenthetical: (Group author [Abbreviation], Publication Year)

Narrative: American Psychological Association (APA, 2008)

Parenthetical: (American Psychological Association [APA], 2018)

No author/Anonymous author

If a reference does not have an author, add the title of the work in in-text citations in place of the author’s name. In general, citations for no author reference appear parenthetical. You need to write the title according to how it is listed in the reference list entry. If the title in the reference list entry is italicized, you need to italicize the title in the in-text citation too. If formatting is not used in the list, use double quotes around the title and capitalize significant words.

Parenthetical: (“Title of the Work,” Publication Year)

Parenthetical: (“The Surrogate Mother,” 2018)

If the author of a work is openly mentioned as “Anonymous,” use “Anonymous” as the author.

Parenthetical: (Anonymous, 2004)

Other citations

Multiple citations in one sentence.

If multiple in-text citations appear together, arrange them in alphabetical order in parenthetical citations. Use semicolons to separate citations.

(Anand, 2017; Burner & Amit, 2012; Pitchard, 2004)

If multiple references by the same author group are cited, arrange them chronologically with a comma separator. Note that the chronological citation for the same author group takes the order mentioned in the below example, i.e., n.d., 2006, in press. Here, “n.d.” stands for “no date.”

(Albert, 2012, 2014a, 2014b; Ben & Bell, 2012, in press; Pitchard, n.d., 2004)

Note that the alphabetical arrangement of in-text citations should not be done in narrative citations.

Same surname, same publication year, different initials

If two or more entries in the reference list have the same surname and publication year, but different initials, add initials to the in-text citations to distinguish each author. This will help the reader locate the correct source of the citation. A few examples for your understanding are given below. The letters “F” and “M’ denote the authors’ initials.

Narrative: F. Author Surname (Publication Year)

Narrative: M. Author Surname (Publication Year)

Parenthetical: (F. Author Surname, Publication Year)

Parenthetical: (M. Author Surname, Publication Year)

Narrative: T. Lange (2016)

Narrative: K. Lange (2016)

Parenthetical: (T. Lange, 2016)

Parenthetical: (K. Lange, 2016)

Same surname, same initials, same publication year

If two or more entries in the reference list have the same surname and initials and same publication year, add a lowercase letter after the year to distinguish the citations. This will help the reader locate the correct source of a citation. A few examples for your understanding are given below.

Narrative: Author Surname (Publication Year followed by a suffix)

Narrative: Author Surname (Publication Year followed by a different suffix)

Parenthetical: (Author Surname, Publication Year followed by a suffix)

Parenthetical: (Author Surname, Publication Year followed by a different suffix)

Narrative: Sullivan (2014a)

Narrative: Sullivan (2014b)

Parenthetical: (Sullivan, 2014a)

Parenthetical: (Sullivan, 2014b)

Translated work

Translated titles contain two publication years (original work publication year and the translated work publication year). Include both years in in-text citations with the original work’s publication year first and the translated work’s publication year next. Separate them with a slash.

Narrative: Author Surname (Publication Year of the original work/Publication Year of the translated work)

Parenthetical: (Author Surname, Publication Year of the original work/Publication Year of the translated work)

Narrative: Herman (1997/2007)

Parenthetical: (Herman, 1997/2007)

Personal communication

Works such as personal interviews, emails, chats, text messages, and conversations on the telephone do not have any source. Such works are cited under personal communication. As the information cannot be retrieved, there will not be a citation for such references in the reference list. When citing personal communication, use initials as well. Try to give the exact date when citing personal communication.

Narrative: Communicator’s name (personal communication, Month Day, Year)

Parenthetical: (Communicator’s name, personal communication, Month Day, Year)

Narrative: K. Sethusankar (personal communication, December 2, 1996)

Parenthetical: (K. Sethusankar, personal communication, December 2, 1996)

For additional information on APA format, select from one of the source types below. For help creating APA citations, check out the BibMe APA citation generator.

Source Types:

• How to cite a Book in APA
• How to cite a Magazine in APA
• How to cite a Newspaper in APA
• How to cite a Website in APA
• How to cite a Journal Article in APA
• How to cite a Film in APA
• How to cite an Interview in APA
• How to cite a Lecture in APA
• How to cite a TV Show / Radio Broadcast in APA
• How to cite an Encyclopedia in APA
• How to cite a Photograph in APA
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Video: The Basics of APA In-text Citations

About In-Text Citations

When writing your papers, it essential to recognize other authors who contributed to your work and avoid plagiarism. 

Use in-text citations when:

• paraphrasing
• directly quoting 
• referring to another person’s writing
• referring to data from prior studies
• reusing tables, figures, images, or passages

These should always include the author’s last name and year. When using a direct quote, also include the page number.

Types of In-Text Citation

• Paraphrasing or Summarizing
• Missing Information

When paraphrasing or summarizing information, in-text citations must include the author's last name and year of publication. This will be in parenthesis at the end of a sentence, with a space between the name and year, and a comma after the name. 

Example 1: single author

Falsely balanced news coverage can distort the public’s perception of expert consensus on an issue (Koehler, 2016).

Example 2: more than one author

Two authors: (Koehler & Smith, 2016)​

Three or more authors: (Koehler et al., 2016)

As an alternative to parenthetical citations, you can cite the source in your narrative, which allows you to incorporate the authors more closely into your discussion:

Example 3: narrative citation

Koehler (2016) noted the dangers of falsely balanced news coverage.​

When using direct quotations in your paper, your in-text citation should also include a page number when available. The page number will come after the year, with a comma after the year. Longer quotations are to be formatted as a block quotation, meaning the entire quotation starts on a separate line and is indented 0.5 inches. Quotations can also be in narrative format. 

Example 1: short quotation (less than 40 words)

Effective teams can be difficult to describe because “high performance along one domain does not translate to high performance along another” (Ervin et al., 2018, p. 470).​

Example 2: block quotation (40 or more words)

Researchers have studied how people talk to themselves:​

​Inner speech is a paradoxical phenomenon. It is an experience that is central to many people’s everyday lives, and yet it presents considerable challenges to any effort to study it scientifically. Nevertheless, a wide range of methodologies and approaches have combined to shed light on the subjective experience of inner speech and its cognitive and neural underpinnings (Alderson-Day & Fernyhough, 2015, p. 957).

Example 3: block quotation in narrative form

Flores et al. (2018) described how they addressed potential researcher bias when working with an intersectional community of transgender people of color:​

Everyone on the research team belonged to a stigmatized group but also held privileged identities. Throughout the research process, we attended to the ways in which our privileged and oppressed identities may have influenced the research process, findings, and presentation of results. (p. 311)

Use the chart below to determine what to do if you are missing information for in-text citation.

Online Resource

• APA.org: In-Text Citations View elements to utilizing in-text citations, including paraphrasing, parenthetical vs. narrative in-text citations, secondary sources, and more.
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In-Text Citations

In scholarly writing, it is essential to acknowledge how others contributed to your work. By following the principles of proper citation, writers ensure that readers understand their contribution in the context of the existing literature—how they are building on, critically examining, or otherwise engaging the work that has come before.

APA Style provides guidelines to help writers determine the appropriate level of citation and how to avoid plagiarism and self-plagiarism.

We also provide specific guidance for in-text citation, including formats for interviews, classroom and intranet sources, and personal communications; in-text citations in general; and paraphrases and direct quotations.

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• Harvard In-Text Citation | A Complete Guide & Examples

Harvard In-Text Citation | A Complete Guide & Examples

Published on 30 April 2020 by Jack Caulfield . Revised on 5 May 2022.

An in-text citation should appear wherever you quote or paraphrase a source in your writing, pointing your reader to the full reference .

In Harvard style , citations appear in brackets in the text. An in-text citation consists of the last name of the author,  the year of publication, and a page number if relevant.

Up to three authors are included in Harvard in-text citations. If there are four or more authors, the citation is shortened with et al .

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Table of contents

Including page numbers in citations, where to place harvard in-text citations, citing sources with missing information, frequently asked questions about harvard in-text citations.

When you quote directly from a source or paraphrase a specific passage, your in-text citation must include a page number to specify where the relevant passage is located.

Use ‘p.’ for a single page and ‘pp.’ for a page range:

• Meanwhile, another commentator asserts that the economy is ‘on the downturn’ (Singh, 2015, p. 13 ).
• Wilson (2015, pp. 12–14 ) makes an argument for the efficacy of the technique.

If you are summarising the general argument of a source or paraphrasing ideas that recur throughout the text, no page number is needed.

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When incorporating citations into your text, you can either name the author directly in the text or only include the author’s name in brackets.

Naming the author in the text

When you name the author in the sentence itself, the year and (if relevant) page number are typically given in brackets straight after the name:

Naming the author directly in your sentence is the best approach when you want to critique or comment on the source.

Naming the author in brackets

When you  you haven’t mentioned the author’s name in your sentence, include it inside the brackets. The citation is generally placed after the relevant quote or paraphrase, or at the end of the sentence, before the full stop:

Multiple citations can be included in one place, listed in order of publication year and separated by semicolons:

This type of citation is useful when you want to support a claim or summarise the overall findings of sources.

Common mistakes with in-text citations

In-text citations in brackets should not appear as the subject of your sentences. Anything that’s essential to the meaning of a sentence should be written outside the brackets:

• (Smith, 2019) argues that…
• Smith (2019) argues that…

Similarly, don’t repeat the author’s name in the bracketed citation and in the sentence itself:

• As Caulfield (Caulfield, 2020) writes…
• As Caulfield (2020) writes…

Sometimes you won’t have access to all the source information you need for an in-text citation. Here’s what to do if you’re missing the publication date, author’s name, or page numbers for a source.

If a source doesn’t list a clear publication date, as is sometimes the case with online sources or historical documents, replace the date with the words ‘no date’:

When it’s not clear who the author of a source is, you’ll sometimes be able to substitute a corporate author – the group or organisation responsible for the publication:

When there’s no corporate author to cite, you can use the title of the source in place of the author’s name:

No page numbers

If you quote from a source without page numbers, such as a website, you can just omit this information if it’s a short text – it should be easy enough to find the quote without it.

If you quote from a longer source without page numbers, it’s best to find an alternate location marker, such as a paragraph number or subheading, and include that:

A Harvard in-text citation should appear in brackets every time you quote, paraphrase, or refer to information from a source.

The citation can appear immediately after the quotation or paraphrase, or at the end of the sentence. If you’re quoting, place the citation outside of the quotation marks but before any other punctuation like a comma or full stop.

In Harvard referencing, up to three author names are included in an in-text citation or reference list entry. When there are four or more authors, include only the first, followed by ‘ et al. ’

In Harvard style , when you quote directly from a source that includes page numbers, your in-text citation must include a page number. For example: (Smith, 2014, p. 33).

You can also include page numbers to point the reader towards a passage that you paraphrased . If you refer to the general ideas or findings of the source as a whole, you don’t need to include a page number.

When you want to use a quote but can’t access the original source, you can cite it indirectly. In the in-text citation , first mention the source you want to refer to, and then the source in which you found it. For example:

It’s advisable to avoid indirect citations wherever possible, because they suggest you don’t have full knowledge of the sources you’re citing. Only use an indirect citation if you can’t reasonably gain access to the original source.

In Harvard style referencing , to distinguish between two sources by the same author that were published in the same year, you add a different letter after the year for each source:

• (Smith, 2019a)
• (Smith, 2019b)

Add ‘a’ to the first one you cite, ‘b’ to the second, and so on. Do the same in your bibliography or reference list .

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Caulfield, J. (2022, May 05). Harvard In-Text Citation | A Complete Guide & Examples. Scribbr. Retrieved 9 September 2024, from https://www.scribbr.co.uk/referencing/harvard-in-text-citation/

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Using In-text Citation

Include an in-text citation when you refer to, summarize, paraphrase, or quote from another source. For every in-text citation in your paper, there must be a corresponding entry in your reference list.

APA in-text citation style uses the author's last name and the year of publication, for example: (Field, 2005). For direct quotations, include the page number as well, for example: (Field, 2005, p. 14). For sources such as websites and e-books that have no page numbers , use a paragraph number, for example: (Field, 2005, para. 1). More information on direct quotation of sources without pagination is given on the APA Style and Grammar Guidelines web page.

Example paragraph with in-text citation

A few researchers in the linguistics field have developed training programs designed to improve native speakers' ability to understand accented speech (Derwing et al., 2002; Thomas, 2004). Their training techniques are based on the research described above indicating that comprehension improves with exposure to non-native speech.   Derwing et al. (2002) conducted their training with students preparing to be social workers, but note that other professionals who work with non-native speakers could benefit from a similar program.

Derwing, T. M., Rossiter, M. J., & Munro, M. J. (2002). Teaching native speakers to listen to foreign-accented speech.  Journal of Multilingual and Multicultural Development , 23 (4), 245-259.

Thomas, H. K. (2004).  Training strategies for improving listeners' comprehension of foreign-accented speech  (Doctoral dissertation). University of Colorado, Boulder.

Citing Web Pages In Text

Cite web pages in text as you would any other source, using the author and date if known. Keep in mind that the author may be an organization rather than a person. For sources with no author, use the title in place of an author.

For sources with no date use n.d. (for no date) in place of the year: (Smith, n.d.). For more information on citations for sources with no date or other missing information see the page on missing reference information on the APA Style and Grammar Guidelines web page. 

Below are examples of using in-text citation with web pages.

Web page with author:

In-text citation

Heavy social media use can be linked to depression and other mental disorders in teens (Asmelash, 2019).

Reference entry

Asmelash, L. (2019, August 14). Social media use may harm teens' mental health by disrupting positive activities, study says . CNN. https://www.cnn.com/2019/08/13/health/social-media-mental-health-trnd/index.html

Web page with organizational author:

More than 300 million people worldwide are affected by depression (World Health Organization, 2018).

World Health Organization. (2018, March 22).  Depression . https://www.who.int/en/news-room/fact-sheets/detail/depression

Web page with no date:

Establishing regular routines, such as exercise, can help survivors of disasters recover from trauma (American Psychological Association [APA], n.d.).

American Psychological Association. (n.d.). Recovering emotionally from disaste r. http://www.apa.org/helpcenter/recovering-disasters.aspx

General Guidelines

In-text references should immediately follow the title, word, or phrase to which they are directly relevant, rather than appearing at the end of long clauses or sentences. In-text references should always precede punctuation marks. Below are examples of using in-text citation.

Author's name in parentheses:

One study found that the most important element in comprehending non-native speech is familiarity with the topic (Gass & Varonis, 1984).

Author's name part of narrative:

Gass and Varonis (1984) found that the most important element in comprehending non-native speech is familiarity with the topic.

Group as author: First citation: (American Psychological Association [APA], 2015) Subsequent citation: (APA, 2015)

Multiple works: (separate each work with semi-colons)

Research shows that listening to a particular accent improves comprehension of accented speech in general (Gass & Varonis, 1984; Krech Thomas, 2004).

Direct quote: (include page number and place quotation marks around the direct quote)

One study found that “the listener's familiarity with the topic of discourse greatly facilitates the interpretation of the entire message” (Gass & Varonis, 1984, p. 85).

Gass and Varonis (1984) found that “the listener’s familiarity with the topic of discourse greatly facilitates the interpretation of the entire message” (p. 85).

Note:  For direct quotations of more than 40 words , display the quote as an indented block of text without quotation marks and include the authors’ names, year, and page number in parentheses at the end of the quote. For example:

This suggests that familiarity with nonnative speech in general, although it is clearly not as important a variable as topic familiarity, may indeed have some effect. That is, prior experience with nonnative speech, such as that gained by listening to the reading, facilitates comprehension. (Gass & Varonis, 1984, p. 77)

Works by Multiple Authors

APA style has specific rules for citing works by multiple authors. Use the following guidelines to determine how to correctly cite works by multiple authors in text. For more information on citing works by multiple authors see the APA Style and Grammar Guidelines page on in-text citation .

Note: When using multiple authors' names as part of your narrative, rather than in parentheses, always spell out the word and. For multiple authors' names within a parenthetic citation, use &.

One author: (Field, 2005)

Two authors: (Gass & Varonis, 1984)

Three or more authors:   (Tremblay et al., 2010)

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In-text citations are inserted in the body of your research paper to briefly document the source of your information. 

• In-text citations in MLA style follow the general format of author's last name followed by a page number enclosed in parentheses. Here is an example: "Here's a direct quote" (Smith 8).
• If the author's name is not given, use the first word (or words) of the title. Follow the same formatting that is used in the works-cited list, such as quotation marks. Here is an example: This is a paraphrase ("Trouble" 22).
• If the source does not have page numbers (for example, some online articles, websites and e-books), only include the author's name for the in-text citation. Do not estimate or make up page numbers.  
• In-text citations point the reader to the works-cited list, which is located at the end of your paper, for more complete bibliographic information.

Repeated Use of Sources

If you use information from a single source more than once in succession (i.e., no other sources referred to in between), you can use a simplified in-text citation. Here is an example:

Cell biology is an area of science that focuses on the structure and function of cells (Smith 15). It revolves around the idea that the cell is a "fundamental unit of life" (17).

  Note: If using this simplified in-text citation creates ambiguity regarding the source being referred to, use the full in-text citation format.

In-Text Citation Formatting and Examples

Format:  (Author's Last Name Page Number)

Example: (Hunt 358)

Two Authors

Format:  (Author's Last Name and Author's Last Name Page Number)

Example: (Case and Daristotle 57)

Three or More Authors

Format:   (Author's Last Name et al. Page Number)

Example: (Case et al. 57)

Unknown Author

Where you would normally put the author's last name, instead use the first one, two, or three words from the title. Do not use  initial articles such as "A", "An" or "The". Provide enough words to clarify which sources from your works-cited list that you are referencing. 

Follow the formatting of the title. For example, if the title in the works-cited list is in italics, italicize the words from the title in the in-text citation, and if the title in the works-cited list is in quotation marks, put quotation marks around the words from the title in the in-text citation.

Format: (Title Page Number)

Examples : 

( Cell Biology 12)

("Nursing" 12)

Multiple Sources

To cite more than one source when you are paraphrasing, separate the in-text citations with a semi-colon.

Format: (Author's Last Name Page Number; Author's Last Name Page Number).

(Smith 42; Bennett 71). 

( It Takes Two ; Brock 43).

 Note: In MLA style, the sources within the in-text citation do not need to be in alphabetical order.

Works Quoted in Another Source

Sometimes an author of a book, article or website will mention another person's work by using a quotation or paraphrased idea from that source. (This may be a secondary source.) For example, the Kirkey article you are reading includes a quotation by Smith that you would like to include in your essay. The basic rule is that in both your Works-Cited List and in-text citation you will still cite Kirkey. Kirkey will appear in your Works Cited list – NOT Smith. Add the words "qtd. in" to your in-text citation.

Examples of in-text citations:

According to a study by Smith (qtd. in Kirkey) 42% of doctors would refuse to perform legal euthanasia.

Smith (qtd. in Kirkey) states that “even if euthanasia was legal, 42% of doctors would be against this method of assisted dying” (A.10).

Example of Works Cited List citation:

Kirkey, Susan. "Euthanasia."   The Montreal Gazette , 9 Feb. 2013, p. A.10. Canadian Newsstand Major Dailies.

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Citation Examples for APA, MLA, and Chicago Style Guides

You may think citing sources for research papers is confusing . . . because it absolutely is! It’s one thing to memorize the precise format for your sources’ information, but it’s another thing to know the precise formats required by APA, MLA, and Chicago style guides.

Because different styles have different citation formats, we thought showing you some citation examples in research papers would help you learn to tell the difference. Feel free to use this guide as a resource to help you get the perfect citation, no matter what style you use.

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How to use citation examples in research

In-text citations vs. full citations, parenthetical citations vs. narrative citations, apa citation examples, apa in-text citation examples, apa citation examples: book.

• APA citation examples: Journal Article

APA citation examples: Website

Apa citation examples: video, apa citation examples: ai, mla citation examples, mla in-text citation examples, mla citation examples: book.

• MLA citation examples: Journal Article

MLA citation examples: Website

Mla citation examples: video, mla citation examples: ai, chicago citation examples, chicago in-text citation examples, chicago citation examples: book.

• Chicago citation examples: Journal Article

Chicago citation examples: Website

Chicago citation examples: video, chicago citation examples: ai, citation examples for multiple authors, apa citation examples for more than one author, mla citation examples for more than one author, chicago citation examples for more than one author.

In academic writing like research papers , you must cite your source for each piece of information that’s not your own . In informal writing like personal essays, you are your own source, so you don’t need a citation. But for writing that uses information from outside books, articles, websites, videos, or even AI, citations are necessary.

The tricky part is that each style has its own particular way of citing sources. Most academic papers are written in one of the three main styles:

• Chicago format

Each of these styles has different rules for what information to include in citations, as well as unique guidelines for particulars like capitalization, the use of italics, and the order in which the information comes. (For more details, read our direct comparison of MLA vs. APA .)

In this blog post, we share citation examples of each style for different types of sources. But first, let’s talk a little about the different types of citations you’ll be using in formal writing.

The two main types of citations are in-text citations and full citations.

In-text citations appear in the body text of the paper and provide the bare minimum of information to identify the source. These usually include the author’s name and sometimes a page number or publication date. They can be either parenthetical or narrative, which we explain below. Alternatively, if you’re using Chicago style, you have the option to use footnotes as in-text citations.

Full citations appear in the bibliography at the end of the text and contain all the relevant information from a source. The idea is that, if your reader is interested in learning more about one of your sources, they can find it in the full citation. Full citations are written in a particular way, and different styles have their own rules for what information goes where.

In APA, the bibliography is called a reference page ; in MLA, it’s called a works cited page . Only Chicago uses the term “bibliography.”

In-text citations can be either parenthetical citations or narrative citations. A parenthetical citation puts a brief credit in parentheses after the related piece of information. Here’s an in-text citation example in APA:

Not all experiments use a placebo group because “if your patients are ill, you shouldn’t be leaving them untreated simply because of your own mawkish interest in the placebo effect” (Goldacre, 2008, p. 60) .

A narrative citation, on the other hand, gives credit in the body text itself, such as by mentioning the author by name. Typically, any information not included in the text is still placed in an abbreviated parenthetical citation afterward.

Not all experiments use a placebo group because, as Ben Goldacre wrote , “if your patients are ill, you shouldn’t be leaving them untreated simply because of your own mawkish interest in the placebo effect” (2008, p. 60) .

Our in-text citation examples below are for standard parenthetical citations. Just remember if you mention the author, page, or year in the main text, you can remove it from the parenthetical citation.

In-text citations in APA use what’s called the author-date style , which includes the author’s last name and the year of publication, separated with commas.

If citing a specific piece of information or a direct quote, also include the location, such as a page number or timestamp. Use the abbreviations p. for page , pp. for pages , and paras. for paragraphs . For general information, such as a concept discussed throughout the source, no location is needed.

(Last Name, Year, p. #)

(Goldacre, 2008, p. 60)

To cite a book in APA , you need the author’s name, year of publication, book title, and publisher. The author’s name is written as “last name, first name initial,” as in “Shakespeare, W.” Titles use sentence-style capitalization, which means only the first letter of the first word in the title (and subtitle, if applicable) are capitalized. If the book edition is relevant, place it in parentheses after the title.

Last name, First name initial. (Year of publication). Title . Publisher.

Goldacre, B. (2008). Bad science. Fourth Estate.

APA citation examples: Journal article

Citing an article in APA requires the author’s last name and first initial; the full date of publication, including month and day if applicable; and the titles of both the article and the journal/periodical, as well as the page number. Note that, unlike MLA and Chicago styles, APA doesn’t abbreviate months in citations.

Last name, First name initial. (Year, Month Day of publication). Article title. Magazine name, volume (issue), page range. DOI

Cardanay, A. (2016, January 12). Illustrating motion, music, and story. General Music Today, 29 (3), 25–29. doi:10.1177/1048371315626498

To cite a website in APA , follow the same format you use to cite journal articles, except without volume, issue, or page numbers. Website citations in APA include a URL, however. If the website represents a print publication, italicize the title. If not, italicize the article name.

Last name, First name initial. (Year, Month Day of publication). Title of article, post, or page. Website. URL

Hudson, J. (2023, November 12). What Taylor Swift can teach us about leadership. Forbes . https://www.forbes.com/sites/jameshudson/2023/11/12/what-taylor-swift-can-teach-us-about-leadership/

To cite YouTube in APA , as well as any online video, you need to include both the uploader’s real name and username, the date posted, the video title, the website name, and the URL. You also need to include the word “Video” in brackets after the video title to show what kind of source it is.

Real last name, First initial. [Username]. (Year, Month Day). Video title [Video]. Website. URL.

Desmond, W. [TED-Ed]. (2019, December 19). The philosophy of cynicism [Video]. YouTube. https://www.youtube.com/watch?v=Utzym1I_BiY

According to the APA website, AI citations in APA should be treated as an “algorithm’s output.” You cite the company that built it as the author, the name of the AI as the title, and the year you interacted with it as the date of publication. You should also include the version you used and a descriptor like “large language model” in brackets, followed by the URL.

Company. (Year). AI Name (version) [Descriptor]. URL

OpenAI. (2023). ChatGPT (March 14 version) [Large language model]. https://chat.openai.com/chat

For MLA, in-text citations use only the author’s last name and the page number or timestamp, without abbreviations or commas.

(Last name #)

(Goldacre 60)

To cite a book in MLA , you need the author’s name, book title, place of publication, publisher’s name, and the date of publication. The author’s name is inverted, with the last name coming before the first name. Most parts are separated by periods, except for the author’s names and publication information, which are separated by commas. Titles use title capitalization, which capitalizes the first letter of each major word.

Last name, First name. Book Title . Place of publication, Publisher, publication date.

Goldacre, Ben. Bad Science . London, Fourth Estate, 2008.

MLA citation examples: Journal article

Citing an article in MLA is similar to citing a journal article in other styles, although MLA uses abbreviations for volume (vol.) and issue number (no.), as well as pages (pp.). If you found the article online, you also need to include the database name in italics and the URL or DOI.

Last name, First name. “Title of article.” Journal , vol. #, no. #, Day Month Year of publication, pp. #–#. Database , DOI or URL.

Cardanay, Audrey. “Illustrating Motion, Music, and Story.” General Music Today , vol. 29, no. 3, 2016, pp. 25–29. Academic Search Premier , doi:10.1177/1048371315626498.

To cite a website in MLA , include the page or article title in quotes and the name of the website in italics. In addition to the publication date and URL, you also need to mention the date you visited the website, using the word “Accessed.”

Last name, First name. “Page or Article Title.” Website , Day Month Year of publication, URL. Accessed Day Month Year.

Hudson, James. “What Taylor Swift Can Teach Us about Leadership.” Forbes , 12 Nov. 2023, https://www.forbes.com/sites/jameshudson/2023/11/12/what-taylor-swift-can-teach-us-about-leadership/. Accessed 13 Nov. 2023.

Citing YouTube in MLA is similar to citing videos in APA, although the information goes in different places. Additionally, you need either the creator’s real name or username, but not both.

Username or Last name, First name. “Title.” Website , Day Month Year, URL.

Desmond, William. “The Philosophy of Cynicism.” YouTube , 19 Dec. 2019, https://www.youtube.com/watch?v=Utzym1I_BiY.

AI citations in MLA ignore the author altogether and use the AI prompt (what you typed into the chat) as the title. MLA uses “containers” for sources within larger works, and for AI the container is the name of the AI. You also need the version, company (as the publisher), date accessed, and URL.

“Entered text” prompt. AI Name , version, Company, Day Month Year, URL.

“Citation examples for research” prompt. ChatGPT , GPT-4, OpenAI, 15 Nov. 2023, chat.openai.com/chat.

In Chicago, you can choose either parenthetical citations or footnotes for in-text citations. Chicago’s parenthetical citations also use an author-date style just like APA citations; however, there is no comma between the author and year (although there is a comma between the year and the location). Chicago citations do not use abbreviations for page numbers.

(Last Name Year, #)

(Goldacre 2008, 60)

Citing a book in Chicago uses the author’s name, book title, place of publication, publisher, and year of publication. You also include the edition, but only if it’s relevant. The author’s name is inverted, and the title uses title capitalization.

Last Name, First Name. Book Title: Subtitle . Edition (if applicable). Place of Publication: Publisher, Year.

Goldacre, Ben. Bad Science . London: Fourth Estate, 2008.

Chicago citation examples: Journal article

Citing an article in Chicago is most similar to citing an article in MLA, including the type of information to include and the use of abbreviations. Pay attention to the citation examples to see the correct order and punctuation to use; note that in Chicago the volume number directly follows the journal title and is not separated by a comma or preceded by the word “vol.”

Last name, First name. “Article title.” Journal vol. #, no. # (Year): #–#. Database or article URL.

Cardanay, Audrey. “Illustrating Motion, Music, and Story.” General Music Today 29, no. 3 (2016): 25–29. Academic Search Premier.

Compared to citing a website in other styles, citing a website in Chicago is more straightforward. Include all the relevant information, put the article or page title in quotations, and don’t worry about italics or the date you visited (unless the website does not have a publication date; in that case, include the date you accessed the site where you would normally put the publication date).

Last name, First name. “Article or Page Title.” Website, Month Day, Year of publication. URL.

Hudson, James. “What Taylor Swift Can Teach Us about Leadership.” Forbes, Nov. 12, 2023. https://www.forbes.com/sites/jameshudson/2023/11/12/what-taylor-swift-can-teach-us-about-leadership/

To cite YouTube in Chicago , you need to include all the standard information, such as the creator’s name, the title of the video, and the website that hosts it, as well as the date and URL. Unlike other formats, Chicago also requires the total video length written in XX:XX format. You also need to mention the source format (“video”) after naming the website.

Uploader. “Title.” Website and format, duration. Month Day, Year of publication. URL.

TED-Ed. “The Philosophy of Cynicism.” YouTube video, 5:25. Dec. 19, 2019. https://www.youtube.com/watch?v=Utzym1I_BiY.

AI citations in Chicago work differently than in other styles; Chicago considers AI conversations as “personal communication” because they’re non-retrievable—meaning other people can’t access the same conversation you had. Consequently, do not include AI chatbots in the bibliography ; mention them only as personal communications if necessary.

However, you still need to use in-text citations for AI in Chicago. For parenthetical citations, you can use the name of the AI as the author and when you had the conversation as the publication date.

APA, MLA, and Chicago formats all have different guidelines for citing more than one author. Here are some quick reference tips on how each does it:

Each author in an APA citation is written in the format of Last name, First Initial. Place authors in the same order as the publication lists them, which may not necessarily be alphabetical. Separate each name with a comma and add an ampersand (&) before the last author’s name.

Marieb, E., & Keller, S. (2018). Essentials of human anatomy & physiology (12th ed.) . Pearson.

In-text citations in APA for two authors use both authors’ last names, connected with an ampersand. For more than two authors, use only the first author’s last name and the phrase et al.

(Marieb & Keller, 2018)

(Marieb et al., 2018)

If an MLA citation has two authors, list them both in the full citation but invert only the first name. Separate them with a comma and the word and .

Cohn, Rachel, and David Levithan. Dash & Lily’s Book of Dares . Ember Publishing House, 2011.

In-text citations use both last names with and .

(Cohn and Levitation 55)

For more than two authors, use only the first author’s name and the phrase et al. in both the full and in-text citation.

Heffernan, James, et al. Writing: A College Handbook . New York, W. W. Norton & Company, 2000.

(Heffernan et al. 27)

In the bibliography, Chicago citations list the names of up to ten authors, separated by commas and with the word and before the last author. For more than ten authors, list only the first seven and then add et al . Only the first name is inverted.

Gyatso, Tenzin, and Howard Cutler. The Art of Happiness: A Handbook for Living . Norwalk: Easton Press, 1998.

In-text citations list the last names of up to three authors, separated by commas (if there are more than two), and the word and before the final name. For four or more authors, use only the first author’s last name and the phrase et al .

(Gyatso and Cutler 1998)

(Gyatso et al. 1998)

Cite your sources with Grammarly

Do you want to make sure your citations are formatted correctly and that you haven’t mistakenly plagiarized information while writing your paper? Grammarly can help! Get well-formatted APA, MLA, and Chicago-style citations with Grammarly’s free citation generator built by writing experts. You can also check your work against billions of websites with our plagiarism checker so you always know when to cite your sources. Sign up for free to get academic writing support at your fingertips.

APA Citation Style

Citation examples.

• Paper Format
• Style and Grammar Guidelines
• Citation Management Tools
• What's New in the 7th Edition?
• APA Style References Guidelines from the American Psychological Association
• APA Style (OWL - Online Writing Lab, Purdue University)
• Common Reference Examples Handout
• Journal Article
• Magazine Article
• Newspaper Article
• Edited Book Chapter
• Dictionary Entry
• Government Report
• YouTube Video
• Facebook Post
• Webpage on a Website
• Supplemental Reference Examples
• Archival Documents and Collections

Parenthetical citations:  (Grady et al., 2019; Jerrentrup et al., 2018)

Narrative citations:  Grady et al. (2019) and Jerrentrup et al. (2018)

• If a journal article has a DOI, include the DOI in the reference.
• If the journal article does not have a DOI and is from an academic research database, end the reference after the page range (for an explanation of why, see the  database information  page). The reference in this case is the same as for a print journal article.
• Do not include database information in the reference unless the journal article comes from a database that publishes original, proprietary content, such as UpToDate (see an example on the  database information  page).
• If the journal article does not have a DOI but does have a URL that will resolve for readers (e.g., it is from an online journal that is not part of a database), include the URL of the article at the end of the reference.
• If the journal article has an article number instead of a page range, include the article number instead of the page range (as shown in the Jerrentrup et al. example).

Parenthetical citations:  (Rabinowitz, 2019; Sapolsky, 2017)

Narrative citations:  Rabinowitz (2019) and Sapolsky (2017)

• If the book includes a DOI, include the DOI in the reference after the publisher name.
• Do not include the publisher location.
• If the book does not have a DOI and comes from an academic research database, end the book reference after the publisher name. Do not include  database information  in the reference. The reference in this case is the same as for a print book.

Parenthetical citations:  (Schaefer & Shapiro, 2019; Schulman, 2019)

Narrative citations:  Schaefer and Shapiro (2019) and Schulman (2019)

• If a magazine article has a DOI, include the DOI in the reference.
• If the magazine article does not have a DOI and is from an academic research database, end the reference after the page range. Do not include  database information  in the reference. The reference in this case is the same as for a print magazine article.
• If the magazine article does not have a DOI but does have a URL that will resolve for readers (e.g., it is from an online magazine that is not part of a database), include the URL of the article at the end of the reference.
• If the magazine article does not have volume, issue, and/or page numbers (e.g., because it is from an online magazine), omit the missing elements from the reference (as in the Schulman example).

Parenthetical citation:  (Carey, 2019)

Narrative citation:  Carey (2019)

• If the newspaper article is from an academic research database, end the reference after the page range. Do not include  database information  in the reference. The reference in this case is the same as for a print newspaper article.
• If the newspaper article has a URL that will resolve for readers (e.g., it is from an online newspaper), include the URL of the article at the end of the reference.
• If the newspaper article does not have volume, issue, and/or page numbers (e.g., because it is from an online newspaper), omit the missing elements from the reference, as shown in the example.
• If the article is from a news website (e.g., CNN, HuffPost)—one that does not have an associated daily or weekly newspaper—use the format for a  webpage on a website  instead.

Parenthetical citation:  (Aron et al., 2019)

Narrative citation:  Aron et al. (2019)

• If the edited book chapter includes a DOI, include the chapter DOI in the reference after the publisher name.
• If the edited book chapter does not have a DOI and comes from an academic research database, end the edited book chapter reference after the publisher name. Do not include  database information  in the reference. The reference in this case is the same as for a print edited book chapter.
• Do not create references for chapters of authored books. Instead, write a reference for the whole book and cite the chapter in the text if desired (e.g., Kumar, 2017, Chapter 2).

Parenthetical citation:  (Merriam-Webster, n.d.)

Narrative citation:  Merriam-Webster (n.d.)

• Because entries in  Merriam-Webster’s Dictionary  are updated over time and are not archived, include a  retrieval date  in the reference.
• Merriam-Webster is both the author and the publisher, so the name appears in the author element only to avoid repetition.
• To quote a dictionary definition, view the pages on quotations and  how to quote works without page numbers  for guidance. Additionally, here is an example:  Culture  refers to the “customary beliefs, social forms, and material traits of a racial, religious, or social group” (Merriam-Webster, n.d., Definition 1a).

Parenthetical citation:  (National Cancer Institute, 2019)

Narrative citation:  National Cancer Institute (2019)

The specific agency responsible for the report appears as the author. The names of parent agencies not present in the  group author name  appear in the source element as the publisher. This creates concise in-text citations and complete reference list entries.

Parenthetical citation:  (Harvard University, 2019)

Narrative citation:  Harvard University (2019)

• Use the name of the account that uploaded the video as the author.
• If the account did not actually create the work, explain this in the text if it is important for readers to know. However, if that would mean citing a source that appears unauthoritative, you might also look for the author’s YouTube channel, official website, or other social media to see whether the same video is available elsewhere.

Parenthetical citations:  (APA Databases, 2019; Gates, 2019)

Narrative citations:  APA Databases (2019) and Gates (2019)

• Present the name of the individual or group author the same as you would for any other reference. Then provide the Twitter handle (beginning with the @ sign) in square brackets, followed by a period.
• Provide the first 20 words of the tweet as the title. Count a URL, a hashtag, or an emoji as one word each, and include them in the reference if they fall within the first 20 words.
• If the tweet includes an image, a video, a poll, or a thumbnail image with a link, indicate that in brackets after the title: [Image attached], [Video attached], [Thumbnail with link attached].
• The same format used for Twitter is also used for Instagram.  

Parenthetical citation:  (News From Science, 2019)

Narrative citation:  News From Science (2019)

• Provide the first 20 words of the Facebook post as the title. Count a URL or other link, a hashtag, or an emoji as one word each, and include them in the reference if they fall within the first 20 words. 
• If a status update includes images, videos, thumbnail links to outside sources, or content from another Facebook post (such as when sharing a link), indicate that in square brackets.

Parenthetical citations:  (Fagan, 2019; National Institute of Mental Health, 2018; Woodyatt, 2019; World Health Organization, 2018)

Narrative citations:  Fagan (2019), National Institute of Mental Health (2018), Woodyatt (2019), and World Health Organization (2018)

• Provide as specific a  date  as is available on the webpage. This might be a year only; a year and month; or a year, month, and day.
• Italicize the title of a webpage.
• When the author of the webpage and the publisher of the website are the same, omit the publisher name to avoid repetition (as in the World Health Organization example).
• When contents of a page are meant to be updated over time but are not archived, include a  retrieval date  in the reference (as in the Fagan example).
• Use the webpage on a website format for articles from news websites such as CNN and HuffPost (these sites do not have associated daily or weekly newspapers). Use the  newspaper article category  for articles from newspaper websites such as  The New York Times  or  The Washington Post .
• Create a reference to an open educational resources (OER) page only when the materials are available for download directly (i.e., the materials are on the page and/or can be downloaded as PDFs or other files). If you are directed to another website, create a reference to the specific webpage on that website where the materials can be retrieved. Use this format for material in any OER repository, such as OER Commons, OASIS, or MERLOT.
• Do not create a reference or in-text citation for a whole website. To mention a website in general, and not any particular information on that site, provide the name of the website in the text and include the URL in parentheses. For example, you might mention that you used a website to create a survey.

The following supplemental example references are mention in the  Publication Manual:

• retracted journal or magazine article
• edition of the Diagnostic and Statistical Manual of Mental Disorders (DSM)
• edition of the International Statistical Classification of Diseases and Related Health Problems (ICD)
• religious work
• annotated religious work

Archival document and collections are not presented in the  APA Publication Manual, Seventh Edition . This content is available only on the APA Style website .  This guidance has been expanded from the 6th edition.

Archival sources include letters, unpublished manuscripts, limited-circulation brochures and pamphlets, in-house institutional and corporate documents, clippings, and other documents, as well as such nontextual materials as photographs and apparatus, that are in the personal possession of an author, form part of an institutional collection, or are stored in an archive such as the Archives of the History of American Psychology at the University of Akron or the APA Archives. For any documents like these that are available on the open web or via a database (subscription or nonsubscription), follow the reference templates shown in Chapter 10 of the Publication Manual.

The general format for the reference for an archival work includes the author, date, title, and source. The reference examples shown on this page may be modified for collections requiring more or less specific information to locate materials, for different types of collections, or for additional descriptive information (e.g., a translation of a letter). Authors may choose to list correspondence from their own personal collections, but correspondence from other private collections should be listed only with the permission of the collector.

Keep in mind the following principles when creating references to archival documents and collections:

• As with any reference, the purpose is to direct readers to the source, despite the fact that only a single copy of the document may be available and readers may have some difficulty actually seeing a copy.
• Include as much information as is needed to help locate the item with reasonable ease within the repository. For items from collections with detailed finding aids, the name of the collection may be sufficient; for items from collections without finding aids, more information (e.g., call number, box number, file name or number) may be necessary to help locate the item.
• If several letters are cited from the same collection, list the collection as a reference and provide specific identifying information (author, recipient, and date) for each letter in the in-text citations (see Example 3).
• Use square brackets to indicate information that does not appear on the document.
• Use “ca.” (circa) to indicate an estimated date (see Example 5).
• Use italics for titles of archival documents and collections; if the work does not have a title, provide a description in square brackets without italics.
• Separate elements of the source (e.g., the name of a repository, library, university or archive, and the location of the university or archive) with commas. End the source with a period.
• If a publication of limited circulation is available in libraries, the reference may be formatted as usual for published material, without the archival source.
• Note that private letters (vs. those in an archive or repository) are considered personal communications and cited in the text only.

1. Letter from a repository

Frank, L. K. (1935, February 4). [Letter to Robert M. Ogden]. Rockefeller Archive Center (GEB Series 1.3, Box 371, Folder 3877), Tarrytown, NY, United States.

• Parenthetical citation: (Frank, 1935)
• Narrative citation: Frank (1935)
• Because the letter does not have a title, provide a description in square brackets.

2. Letter from a private collection

Zacharius, G. P. (1953, August 15). [Letter to William Rickel (W. Rickel, Trans.)]. Copy in possession of Hendrika Vande Kemp.

• Parenthetical citation: (Zacharius, 1953)
• Narrative citation: Zacharius (1953)
• In this example, Hendrika Vande Kemp is either the author of the paper or the author of the paper has received permission from Hendrika Vande Kemp to cite a letter in Vande Kemp’s private collection in this way. Otherwise, cite a private letter as a  personal communication .

3. Collection of letters from an archive

Allport, G. W. (1930–1967). Correspondence. Gordon W. Allport Papers (HUG 4118.10), Harvard University Archives, Cambridge, MA, United States.

• Parenthetical citation: (Allport, 1930–1967)
• Narrative citation: Allport (1930–1967)

To cite specific letters in the text, provide the author and range of years as shown in the reference list entry, plus details about who wrote the specific letter to whom and when the specific letter was written.

• Parenthetical citation: (Allport, 1930–1967, G. Boring to Allport, December 26, 1937)
• Narrative citation: Allport (1930–1967, Allport to G. Boring, March 1, 1939)
• Use the parenthetical citation format to cite a letter that E. G. Boring wrote to Allport because Allport is the author in the reference. Use either the parenthetical or narrative citation format to cite letters that Allport wrote.

4. Unpublished papers, lectures from an archive or personal collection

Berliner, A. (1959). Notes for a lecture on reminiscences of Wundt and Leipzig. Anna Berliner Memoirs (Box M50), Archives of the History of American Psychology, University of Akron, Akron, OH, United States.

• Parenthetical citation: (Berliner, 1959)
• Narrative citation: Berliner (1959)

5. Archival/historical source for which the author and/or date is known or is reasonably certain but not stated on the document

Allport, A. (presumed). (ca. 1937). Marion Taylor today—by the biographer [Unpublished manuscript]. Marion Taylor Papers, Schlesinger Library, Radcliffe College, Cambridge, MA, United States.

• Parenthetical citation: (Allport, ca. 1937)
• Narrative citation: Allport (ca. 1937)
• Because the author is reasonably certain but not stated on the document, place the word “presumed” in parentheses after the name, followed by a period.
• Because the date is reasonably certain but not stated on the document, the abbreviation “ca.” (which stands for “circa”) appears before the year in parentheses.

6. Archival source with group author

Subcommittee on Mental Hygiene Personnel in School Programs. (1949, November 5–6). Meeting of Subcommittee on Mental Hygiene Personnel in School Programs. David Shakow Papers (M1360), Archives of the History of American Psychology, University of Akron, Akron, OH, United States.

• Parenthetical citation: (Subcommittee on Mental Hygiene Personnel in School Programs, 1949)
• Narrative citation: Subcommittee on Mental Hygiene Personnel in School Programs (1949)

7. Interview recorded and available in an archive

Smith, M. B. (1989, August 12). Interview by C. A. Kiesler [Tape recording]. President’s Oral History Project, American Psychological Association, APA Archives, Washington, DC, United States.

• Parenthetical citation: (Smith, 1989)
• Narrative citation: Smith (1989)
• For interviews and oral histories recorded in an archive, list the interviewee as the author. Include the interviewer’s name in the description.

8. Transcription of a recorded interview, no recording available

Sparkman, C. F. (1973). An oral history with Dr. Colley F. Sparkman/Interviewer: Orley B. Caudill. Mississippi Oral History Program (Vol. 289), University of Southern Mississippi, Hattiesburg, MS, United States.

• Parenthetical citation: (Sparkman, 1973)
• Narrative citation: Sparkman (1973)

9. Newspaper article clipping, historical, in personal collection

Psychoanalysis institute to open. (1948, September 18). [Clipping from an unidentified Dayton, OH, United States, newspaper]. Copy in possession of author.

• Parenthetical citation: (“Psychoanalysis Institute to Open,” 1948)
• Narrative citation: “Psychoanalysis Institute to Open” (1948)
• Use this format only if you are the person who is in possession of the newspaper clipping.

10. Historical publication of limited circulation

Sci-Art Publishers. (1935). Sci-Art publications [Brochure]. Roback Papers (HUGFP 104.50, Box 2, Folder “Miscellaneous Psychological Materials”), Harvard University Archives, Cambridge, MA, United States.

• Parenthetical citation: (Sci-Art Publishers, 1935)
• Narrative citation: Sci-Art Publishers (1935)

11. Archived photographs, no author and no title

[Photographs of Robert M. Yerkes]. (ca. 1917–1954). Robert Mearns Yerkes Papers (Box 137, Folder 2292), Manuscripts and Archives, Yale University Library, New Haven, CT, United States.

• Parenthetical citation: ([Photographs of Robert M. Yerkes], ca. 1917–1954)
• Narrative citation: [Photographs of Robert M. Yerkes] (ca. 1917–1954)
• Because the archived photographs do not have a title, provide a bracketed description instead.
• Because the archived photographs do not have an author, move the bracketed description to the author position of the reference.

12. Microfilm

U.S. Census Bureau. (1880). 1880 U.S. census: Defective, dependent, and delinquent classes schedule: Virginia [Microfilm]. NARA Microfilm Publication T1132 (Rolls 33–34), National Archives and Records Administration, Washington, DC, United States.

• Parenthetical citation: (U.S. Census Bureau, 1880)
• Narrative citation: U.S. Census Bureau (1880)

Read the full APA guidelines on citing ChatGPT 

OpenAI. (2023).  ChatGPT  (Mar 14 version) [Large language model].  https://chat.openai.com/chat

• Parenthetical citation:  (OpenAI, 2023)
• Narrative citation:  OpenAI (2023)

Author:  The author of the model is OpenAI.

Date:  The date is the year of the version you used. Following the template in Section 10.10, you need to include only the year, not the exact date. The version number provides the specific date information a reader might need.

Title:  The name of the model is “ChatGPT,” so that serves as the title and is italicized in your reference, as shown in the template. Although OpenAI labels unique iterations (i.e., ChatGPT-3, ChatGPT-4), they are using “ChatGPT” as the general name of the model, with updates identified with version numbers.

The version number is included after the title in parentheses. The format for the version number in ChatGPT references includes the date because that is how OpenAI is labeling the versions. Different large language models or software might use different version numbering; use the version number in the format the author or publisher provides, which may be a numbering system (e.g., Version 2.0) or other methods.

Bracketed text  is used in references for additional descriptions when they are needed to help a reader understand what’s being cited. References for a number of common sources, such as journal articles and books, do not include bracketed descriptions, but things outside of the typical peer-reviewed system often do. In the case of a reference for ChatGPT, provide the descriptor “Large language model” in square brackets. OpenAI describes ChatGPT-4 as a “large multimodal model,” so that description may be provided instead if you are using ChatGPT-4. Later versions and software or models from other companies may need different descriptions, based on how the publishers describe the model. The goal of the bracketed text is to briefly describe the kind of model to your reader.

Source:  When the publisher name and the author name are the same, do not repeat the publisher name in the source element of the reference, and move directly to the URL. This is the case for ChatGPT. The URL for ChatGPT is  https://chat.openai.com/chat . For other models or products for which you may create a reference, use the URL that links as directly as possible to the source (i.e., the page where you can access the model, not the publisher’s homepage).

What to include and what to exclude

Works included in a reference list.

The reference list provides a reliable way for readers to identify and locate the works cited in a paper. APA Style papers generally include reference lists, not  bibliographies.

In general, each work cited in the text must appear in the reference list, and each work in the reference list must be cited in the text. Check your work carefully before submitting your manuscript or course assignment to ensure no works cited in the text are missing from the reference list and vice versa, with only the following exceptions.

Works Excluded From a Reference List

There are a few kinds of works that are not included in a reference list. Usually a work is not included because readers cannot recover it or because the mention is so broad that readers do not need a reference list entry to understand the use.

Information on works included in a reference list is covered in Sections 2.12 and 8.4 of the  APA Publication Manual, Seventh Edition

*This guidance has been expanded from the 6th edition.*

• Personal communications  such as emails, phone calls, or text messages are cited in the text only, not in the reference list, because readers cannot retrieve personal communications.
• General mentions of whole websites, whole periodicals, and common software and apps in the text do not require in-text citations or reference list entries because the use is broad and the source is familiar.
• The source of an epigraph does not usually appear in the reference list unless the work is a scholarly book or journal. For example, if you open the paper with an inspirational quotation by a famous person, the source of the quotation does not appear in the reference list because the quotation is meant to set the stage for the work, not substantiate a key point.   
• Quotations from research participants in a study you conducted can be presented and discussed in the text but do not need citations or reference list entries. Citations and reference list entries are not necessary because the quotations are part of your original research. They could also compromise participants’ confidentiality, which is an ethical violation.
• References included in a meta-analysis, which are marked with an asterisk in the reference list, may be cited in the text (or not) at the author’s discretion. This exception is relevant only to authors who are conducting a meta-analysis.

DOIs and URLs

The DOI or URL is the final component of a reference list entry. Because so much scholarship is available and/or retrieved online, most reference list entries end with either a DOI or a URL.

• A DOI is a unique alphanumeric string that identifies content and provides a persistent link to its location on the internet. DOIs can be found in database records and the reference lists of published works.
• A URL specifies the location of digital information on the internet and can be found in the address bar of your internet browser. URLs in references should link directly to the cited work when possible.

Follow these guidelines for including DOIs and URLs in references:

• Include a DOI for all works that have a DOI, regardless of whether you used the online version or the print version.
• If a print work does not have a DOI, do not include any DOI or URL in the reference.
• If an online work has both a DOI and a URL, include only the DOI.
• For works without DOIs from websites (not including academic research databases), provide a URL in the reference (as long as the URL will work for readers).
• For works without DOIs from most  academic research databases , do not include a URL or database information in the reference because these works are widely available. The reference should be the same as the reference for a print version of the work.
• For works from databases that publish original, proprietary material available only in that database (such as the UpToDate database) or for works of limited circulation in databases (such as monographs in the ERIC database), include the name of the database or archive and the URL of the work. If the URL requires a login or is session-specific (meaning it will not resolve for readers), provide the URL of the database or archive home page or login page instead of the URL for the work. See the page on including  database information in references  for more information. 
• If the URL is no longer working or no longer provides readers access to the content you intend to cite, follow the guidance for works with  no source .
• Other alphanumeric identifiers such as the International Standard Book Number (ISBN) and the International Standard Serial Number (ISSN) are not included in APA Style references.

Follow these guidelines to format DOIs and URLs:

• Present both DOIs and URLs as hyperlinks (i.e., beginning with “http:” or “https:”).
• Because a hyperlink leads readers directly to the content, it is not necessary to include the words “Retrieved from” or “Accessed from” before a DOI or URL.
• It is acceptable to use either the default display settings for hyperlinks in your word-processing program (e.g., usually blue font, underlined) or plain text that is not underlined.
• Leave links live if the work is to be published or read online.
• Follow the current recommendations of the International DOI Foundation to format DOIs in the reference list, which as of this publication is as follows:

https://doi.org/ xxxxx

• The string “https://doi.org/” is a way of presenting a DOI as a link, and “xxxxx” refers to the DOI number.
• The preferred format of the DOI has changed over time. Although older works use previous formats (e.g., “http:/dx.doi.org/” or “doi:” or “DOI:” before the DOI number), in your reference list, standardize DOIs into the current preferred format for all entries. For example, use  https://doi.org/10.1037/a0040251  in your reference even though that article, published in 2016, presented the number in an older format.
• Copy and paste the DOI or URL from your web browser directly into your reference list to avoid transcription errors. Do not change the capitalization or punctuation of the DOI or URL. Do not add line breaks manually to the hyperlink; it is acceptable if your word-processing program automatically adds a break or moves the hyperlink to its own line.
• Do not add a period after the DOI or URL because this may interfere with link functionality.

When a DOI or URL is long or complex, you may use shortDOIs or shortened URLs if desired.

• Use the  shortDOI service  provided by the International DOI Foundation to create shortDOIs. A work can have only one DOI and only one shortDOI; the shortDOI service will either produce a new shortDOI for a work that has never had one or retrieve an existing shortDOI.
• Some websites provide their own branded shortened URLs, and independent URL shortening services are available as well. Any shortened URL is acceptable in a reference as long as you check the link to ensure that it takes you to the correct location.
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APA Citation Guide

In-Text Citations

APA Style uses an author-date citation system. In this system, an abbreviation citation appears in the text of your paper which directs readers to the citation in the reference list at the end of the paper. Each source cited in the text of your paper must appear in the reference list, and each source in the reference list must appear in the text of your paper.

Read More on the APA Style Website

Parenthetical vs. Narrative Citations

• In parenthetical citations, the author name(s) and publication date for the source appear in parentheses at the end of a sentence.

...(Kerouac, 1958).

• In narrative citations, the author name is incorporated into the actual text of the paper, with the publication year immediately following in parentheses.

Kerouac (1958) reported...

Multiple Authors and Group Authors

Citing Multiple Sources in the Same Sentence

When citing multiple sources within the same set of parentheses, list the sources alphabetically in the order they appear in your reference list, separated by a semicolon.

• (Allen, 2015; Smith 2009).
• (B. Johnson, 2018; K. Johnson, 2017). ← Use first initials when last names are the same
• (Department of Veterans Affairs, 2001, 2003). ← Multiple sources from same author

Citing Parts of a Source

To cite part of a source, provide the page, page range, chapter, section, or figure/table number after the date in your in-text citation.

• (Centers for Disease Control and Prevention, 2005, p. 10).
• (Daniels, 2013, pp. 175-196).
• (Sakamura, 1999, Chapter 5).
• (American Psychological Association, 2020, para. 3).

For short quotations (fewer than 40 words), simply add quotation marks around the direct quote and incorporate it into your own text. Quotations of 40 words or more require block formatting.

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Peer Reviewed

GPT-fabricated scientific papers on Google Scholar: Key features, spread, and implications for preempting evidence manipulation

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Academic journals, archives, and repositories are seeing an increasing number of questionable research papers clearly produced using generative AI. They are often created with widely available, general-purpose AI applications, most likely ChatGPT, and mimic scientific writing. Google Scholar easily locates and lists these questionable papers alongside reputable, quality-controlled research. Our analysis of a selection of questionable GPT-fabricated scientific papers found in Google Scholar shows that many are about applied, often controversial topics susceptible to disinformation: the environment, health, and computing. The resulting enhanced potential for malicious manipulation of society’s evidence base, particularly in politically divisive domains, is a growing concern.

Swedish School of Library and Information Science, University of Borås, Sweden

Department of Arts and Cultural Sciences, Lund University, Sweden

Division of Environmental Communication, Swedish University of Agricultural Sciences, Sweden

Research Questions

• Where are questionable publications produced with generative pre-trained transformers (GPTs) that can be found via Google Scholar published or deposited?
• What are the main characteristics of these publications in relation to predominant subject categories?
• How are these publications spread in the research infrastructure for scholarly communication?
• How is the role of the scholarly communication infrastructure challenged in maintaining public trust in science and evidence through inappropriate use of generative AI?

research note Summary

• A sample of scientific papers with signs of GPT-use found on Google Scholar was retrieved, downloaded, and analyzed using a combination of qualitative coding and descriptive statistics. All papers contained at least one of two common phrases returned by conversational agents that use large language models (LLM) like OpenAI’s ChatGPT. Google Search was then used to determine the extent to which copies of questionable, GPT-fabricated papers were available in various repositories, archives, citation databases, and social media platforms.
• Roughly two-thirds of the retrieved papers were found to have been produced, at least in part, through undisclosed, potentially deceptive use of GPT. The majority (57%) of these questionable papers dealt with policy-relevant subjects (i.e., environment, health, computing), susceptible to influence operations. Most were available in several copies on different domains (e.g., social media, archives, and repositories).
• Two main risks arise from the increasingly common use of GPT to (mass-)produce fake, scientific publications. First, the abundance of fabricated “studies” seeping into all areas of the research infrastructure threatens to overwhelm the scholarly communication system and jeopardize the integrity of the scientific record. A second risk lies in the increased possibility that convincingly scientific-looking content was in fact deceitfully created with AI tools and is also optimized to be retrieved by publicly available academic search engines, particularly Google Scholar. However small, this possibility and awareness of it risks undermining the basis for trust in scientific knowledge and poses serious societal risks.

Implications

The use of ChatGPT to generate text for academic papers has raised concerns about research integrity. Discussion of this phenomenon is ongoing in editorials, commentaries, opinion pieces, and on social media (Bom, 2023; Stokel-Walker, 2024; Thorp, 2023). There are now several lists of papers suspected of GPT misuse, and new papers are constantly being added. 1 See for example Academ-AI, https://www.academ-ai.info/ , and Retraction Watch, https://retractionwatch.com/papers-and-peer-reviews-with-evidence-of-chatgpt-writing/ . While many legitimate uses of GPT for research and academic writing exist (Huang & Tan, 2023; Kitamura, 2023; Lund et al., 2023), its undeclared use—beyond proofreading—has potentially far-reaching implications for both science and society, but especially for their relationship. It, therefore, seems important to extend the discussion to one of the most accessible and well-known intermediaries between science, but also certain types of misinformation, and the public, namely Google Scholar, also in response to the legitimate concerns that the discussion of generative AI and misinformation needs to be more nuanced and empirically substantiated  (Simon et al., 2023).

Google Scholar, https://scholar.google.com , is an easy-to-use academic search engine. It is available for free, and its index is extensive (Gusenbauer & Haddaway, 2020). It is also often touted as a credible source for academic literature and even recommended in library guides, by media and information literacy initiatives, and fact checkers (Tripodi et al., 2023). However, Google Scholar lacks the transparency and adherence to standards that usually characterize citation databases. Instead, Google Scholar uses automated crawlers, like Google’s web search engine (Martín-Martín et al., 2021), and the inclusion criteria are based on primarily technical standards, allowing any individual author—with or without scientific affiliation—to upload papers to be indexed (Google Scholar Help, n.d.). It has been shown that Google Scholar is susceptible to manipulation through citation exploits (Antkare, 2020) and by providing access to fake scientific papers (Dadkhah et al., 2017). A large part of Google Scholar’s index consists of publications from established scientific journals or other forms of quality-controlled, scholarly literature. However, the index also contains a large amount of gray literature, including student papers, working papers, reports, preprint servers, and academic networking sites, as well as material from so-called “questionable” academic journals, including paper mills. The search interface does not offer the possibility to filter the results meaningfully by material type, publication status, or form of quality control, such as limiting the search to peer-reviewed material.

To understand the occurrence of ChatGPT (co-)authored work in Google Scholar’s index, we scraped it for publications, including one of two common ChatGPT responses (see Appendix A) that we encountered on social media and in media reports (DeGeurin, 2024). The results of our descriptive statistical analyses showed that around 62% did not declare the use of GPTs. Most of these GPT-fabricated papers were found in non-indexed journals and working papers, but some cases included research published in mainstream scientific journals and conference proceedings. 2 Indexed journals mean scholarly journals indexed by abstract and citation databases such as Scopus and Web of Science, where the indexation implies journals with high scientific quality. Non-indexed journals are journals that fall outside of this indexation. More than half (57%) of these GPT-fabricated papers concerned policy-relevant subject areas susceptible to influence operations. To avoid increasing the visibility of these publications, we abstained from referencing them in this research note. However, we have made the data available in the Harvard Dataverse repository.

The publications were related to three issue areas—health (14.5%), environment (19.5%) and computing (23%)—with key terms such “healthcare,” “COVID-19,” or “infection”for health-related papers, and “analysis,” “sustainable,” and “global” for environment-related papers. In several cases, the papers had titles that strung together general keywords and buzzwords, thus alluding to very broad and current research. These terms included “biology,” “telehealth,” “climate policy,” “diversity,” and “disrupting,” to name just a few.  While the study’s scope and design did not include a detailed analysis of which parts of the articles included fabricated text, our dataset did contain the surrounding sentences for each occurrence of the suspicious phrases that formed the basis for our search and subsequent selection. Based on that, we can say that the phrases occurred in most sections typically found in scientific publications, including the literature review, methods, conceptual and theoretical frameworks, background, motivation or societal relevance, and even discussion. This was confirmed during the joint coding, where we read and discussed all articles. It became clear that not just the text related to the telltale phrases was created by GPT, but that almost all articles in our sample of questionable articles likely contained traces of GPT-fabricated text everywhere.

Evidence hacking and backfiring effects

Generative pre-trained transformers (GPTs) can be used to produce texts that mimic scientific writing. These texts, when made available online—as we demonstrate—leak into the databases of academic search engines and other parts of the research infrastructure for scholarly communication. This development exacerbates problems that were already present with less sophisticated text generators (Antkare, 2020; Cabanac & Labbé, 2021). Yet, the public release of ChatGPT in 2022, together with the way Google Scholar works, has increased the likelihood of lay people (e.g., media, politicians, patients, students) coming across questionable (or even entirely GPT-fabricated) papers and other problematic research findings. Previous research has emphasized that the ability to determine the value and status of scientific publications for lay people is at stake when misleading articles are passed off as reputable (Haider & Åström, 2017) and that systematic literature reviews risk being compromised (Dadkhah et al., 2017). It has also been highlighted that Google Scholar, in particular, can be and has been exploited for manipulating the evidence base for politically charged issues and to fuel conspiracy narratives (Tripodi et al., 2023). Both concerns are likely to be magnified in the future, increasing the risk of what we suggest calling evidence hacking —the strategic and coordinated malicious manipulation of society’s evidence base.

The authority of quality-controlled research as evidence to support legislation, policy, politics, and other forms of decision-making is undermined by the presence of undeclared GPT-fabricated content in publications professing to be scientific. Due to the large number of archives, repositories, mirror sites, and shadow libraries to which they spread, there is a clear risk that GPT-fabricated, questionable papers will reach audiences even after a possible retraction. There are considerable technical difficulties involved in identifying and tracing computer-fabricated papers (Cabanac & Labbé, 2021; Dadkhah et al., 2023; Jones, 2024), not to mention preventing and curbing their spread and uptake.

However, as the rise of the so-called anti-vaxx movement during the COVID-19 pandemic and the ongoing obstruction and denial of climate change show, retracting erroneous publications often fuels conspiracies and increases the following of these movements rather than stopping them. To illustrate this mechanism, climate deniers frequently question established scientific consensus by pointing to other, supposedly scientific, studies that support their claims. Usually, these are poorly executed, not peer-reviewed, based on obsolete data, or even fraudulent (Dunlap & Brulle, 2020). A similar strategy is successful in the alternative epistemic world of the global anti-vaccination movement (Carrion, 2018) and the persistence of flawed and questionable publications in the scientific record already poses significant problems for health research, policy, and lawmakers, and thus for society as a whole (Littell et al., 2024). Considering that a person’s support for “doing your own research” is associated with increased mistrust in scientific institutions (Chinn & Hasell, 2023), it will be of utmost importance to anticipate and consider such backfiring effects already when designing a technical solution, when suggesting industry or legal regulation, and in the planning of educational measures.

Recommendations

Solutions should be based on simultaneous considerations of technical, educational, and regulatory approaches, as well as incentives, including social ones, across the entire research infrastructure. Paying attention to how these approaches and incentives relate to each other can help identify points and mechanisms for disruption. Recognizing fraudulent academic papers must happen alongside understanding how they reach their audiences and what reasons there might be for some of these papers successfully “sticking around.” A possible way to mitigate some of the risks associated with GPT-fabricated scholarly texts finding their way into academic search engine results would be to provide filtering options for facets such as indexed journals, gray literature, peer-review, and similar on the interface of publicly available academic search engines. Furthermore, evaluation tools for indexed journals 3 Such as LiU Journal CheckUp, https://ep.liu.se/JournalCheckup/default.aspx?lang=eng . could be integrated into the graphical user interfaces and the crawlers of these academic search engines. To enable accountability, it is important that the index (database) of such a search engine is populated according to criteria that are transparent, open to scrutiny, and appropriate to the workings of  science and other forms of academic research. Moreover, considering that Google Scholar has no real competitor, there is a strong case for establishing a freely accessible, non-specialized academic search engine that is not run for commercial reasons but for reasons of public interest. Such measures, together with educational initiatives aimed particularly at policymakers, science communicators, journalists, and other media workers, will be crucial to reducing the possibilities for and effects of malicious manipulation or evidence hacking. It is important not to present this as a technical problem that exists only because of AI text generators but to relate it to the wider concerns in which it is embedded. These range from a largely dysfunctional scholarly publishing system (Haider & Åström, 2017) and academia’s “publish or perish” paradigm to Google’s near-monopoly and ideological battles over the control of information and ultimately knowledge. Any intervention is likely to have systemic effects; these effects need to be considered and assessed in advance and, ideally, followed up on.

Our study focused on a selection of papers that were easily recognizable as fraudulent. We used this relatively small sample as a magnifying glass to examine, delineate, and understand a problem that goes beyond the scope of the sample itself, which however points towards larger concerns that require further investigation. The work of ongoing whistleblowing initiatives 4 Such as Academ-AI, https://www.academ-ai.info/ , and Retraction Watch, https://retractionwatch.com/papers-and-peer-reviews-with-evidence-of-chatgpt-writing/ . , recent media reports of journal closures (Subbaraman, 2024), or GPT-related changes in word use and writing style (Cabanac et al., 2021; Stokel-Walker, 2024) suggest that we only see the tip of the iceberg. There are already more sophisticated cases (Dadkhah et al., 2023) as well as cases involving fabricated images (Gu et al., 2022). Our analysis shows that questionable and potentially manipulative GPT-fabricated papers permeate the research infrastructure and are likely to become a widespread phenomenon. Our findings underline that the risk of fake scientific papers being used to maliciously manipulate evidence (see Dadkhah et al., 2017) must be taken seriously. Manipulation may involve undeclared automatic summaries of texts, inclusion in literature reviews, explicit scientific claims, or the concealment of errors in studies so that they are difficult to detect in peer review. However, the mere possibility of these things happening is a significant risk in its own right that can be strategically exploited and will have ramifications for trust in and perception of science. Society’s methods of evaluating sources and the foundations of media and information literacy are under threat and public trust in science is at risk of further erosion, with far-reaching consequences for society in dealing with information disorders. To address this multifaceted problem, we first need to understand why it exists and proliferates.

Finding 1: 139 GPT-fabricated, questionable papers were found and listed as regular results on the Google Scholar results page. Non-indexed journals dominate.

Most questionable papers we found were in non-indexed journals or were working papers, but we did also find some in established journals, publications, conferences, and repositories. We found a total of 139 papers with a suspected deceptive use of ChatGPT or similar LLM applications (see Table 1). Out of these, 19 were in indexed journals, 89 were in non-indexed journals, 19 were student papers found in university databases, and 12 were working papers (mostly in preprint databases). Table 1 divides these papers into categories. Health and environment papers made up around 34% (47) of the sample. Of these, 66% were present in non-indexed journals.

Finding 2: GPT-fabricated, questionable papers are disseminated online, permeating the research infrastructure for scholarly communication, often in multiple copies. Applied topics with practical implications dominate.

The 20 papers concerning health-related issues are distributed across 20 unique domains, accounting for 46 URLs. The 27 papers dealing with environmental issues can be found across 26 unique domains, accounting for 56 URLs.  Most of the identified papers exist in multiple copies and have already spread to several archives, repositories, and social media. It would be difficult, or impossible, to remove them from the scientific record.

As apparent from Table 2, GPT-fabricated, questionable papers are seeping into most parts of the online research infrastructure for scholarly communication. Platforms on which identified papers have appeared include ResearchGate, ORCiD, Journal of Population Therapeutics and Clinical Pharmacology (JPTCP), Easychair, Frontiers, the Institute of Electrical and Electronics Engineer (IEEE), and X/Twitter. Thus, even if they are retracted from their original source, it will prove very difficult to track, remove, or even just mark them up on other platforms. Moreover, unless regulated, Google Scholar will enable their continued and most likely unlabeled discoverability.

A word rain visualization (Centre for Digital Humanities Uppsala, 2023), which combines word prominences through TF-IDF 5 Term frequency–inverse document frequency , a method for measuring the significance of a word in a document compared to its frequency across all documents in a collection. scores with semantic similarity of the full texts of our sample of GPT-generated articles that fall into the “Environment” and “Health” categories, reflects the two categories in question. However, as can be seen in Figure 1, it also reveals overlap and sub-areas. The y-axis shows word prominences through word positions and font sizes, while the x-axis indicates semantic similarity. In addition to a certain amount of overlap, this reveals sub-areas, which are best described as two distinct events within the word rain. The event on the left bundles terms related to the development and management of health and healthcare with “challenges,” “impact,” and “potential of artificial intelligence”emerging as semantically related terms. Terms related to research infrastructures, environmental, epistemic, and technological concepts are arranged further down in the same event (e.g., “system,” “climate,” “understanding,” “knowledge,” “learning,” “education,” “sustainable”). A second distinct event further to the right bundles terms associated with fish farming and aquatic medicinal plants, highlighting the presence of an aquaculture cluster.  Here, the prominence of groups of terms such as “used,” “model,” “-based,” and “traditional” suggests the presence of applied research on these topics. The two events making up the word rain visualization, are linked by a less dominant but overlapping cluster of terms related to “energy” and “water.”

The bar chart of the terms in the paper subset (see Figure 2) complements the word rain visualization by depicting the most prominent terms in the full texts along the y-axis. Here, word prominences across health and environment papers are arranged descendingly, where values outside parentheses are TF-IDF values (relative frequencies) and values inside parentheses are raw term frequencies (absolute frequencies).

Finding 3: Google Scholar presents results from quality-controlled and non-controlled citation databases on the same interface, providing unfiltered access to GPT-fabricated questionable papers.

Google Scholar’s central position in the publicly accessible scholarly communication infrastructure, as well as its lack of standards, transparency, and accountability in terms of inclusion criteria, has potentially serious implications for public trust in science. This is likely to exacerbate the already-known potential to exploit Google Scholar for evidence hacking (Tripodi et al., 2023) and will have implications for any attempts to retract or remove fraudulent papers from their original publication venues. Any solution must consider the entirety of the research infrastructure for scholarly communication and the interplay of different actors, interests, and incentives.

We searched and scraped Google Scholar using the Python library Scholarly (Cholewiak et al., 2023) for papers that included specific phrases known to be common responses from ChatGPT and similar applications with the same underlying model (GPT3.5 or GPT4): “as of my last knowledge update” and/or “I don’t have access to real-time data” (see Appendix A). This facilitated the identification of papers that likely used generative AI to produce text, resulting in 227 retrieved papers. The papers’ bibliographic information was automatically added to a spreadsheet and downloaded into Zotero. 6 An open-source reference manager, https://zotero.org .

We employed multiple coding (Barbour, 2001) to classify the papers based on their content. First, we jointly assessed whether the paper was suspected of fraudulent use of ChatGPT (or similar) based on how the text was integrated into the papers and whether the paper was presented as original research output or the AI tool’s role was acknowledged. Second, in analyzing the content of the papers, we continued the multiple coding by classifying the fraudulent papers into four categories identified during an initial round of analysis—health, environment, computing, and others—and then determining which subjects were most affected by this issue (see Table 1). Out of the 227 retrieved papers, 88 papers were written with legitimate and/or declared use of GPTs (i.e., false positives, which were excluded from further analysis), and 139 papers were written with undeclared and/or fraudulent use (i.e., true positives, which were included in further analysis). The multiple coding was conducted jointly by all authors of the present article, who collaboratively coded and cross-checked each other’s interpretation of the data simultaneously in a shared spreadsheet file. This was done to single out coding discrepancies and settle coding disagreements, which in turn ensured methodological thoroughness and analytical consensus (see Barbour, 2001). Redoing the category coding later based on our established coding schedule, we achieved an intercoder reliability (Cohen’s kappa) of 0.806 after eradicating obvious differences.

The ranking algorithm of Google Scholar prioritizes highly cited and older publications (Martín-Martín et al., 2016). Therefore, the position of the articles on the search engine results pages was not particularly informative, considering the relatively small number of results in combination with the recency of the publications. Only the query “as of my last knowledge update” had more than two search engine result pages. On those, questionable articles with undeclared use of GPTs were evenly distributed across all result pages (min: 4, max: 9, mode: 8), with the proportion of undeclared use being slightly higher on average on later search result pages.

To understand how the papers making fraudulent use of generative AI were disseminated online, we programmatically searched for the paper titles (with exact string matching) in Google Search from our local IP address (see Appendix B) using the googlesearch – python library(Vikramaditya, 2020). We manually verified each search result to filter out false positives—results that were not related to the paper—and then compiled the most prominent URLs by field. This enabled the identification of other platforms through which the papers had been spread. We did not, however, investigate whether copies had spread into SciHub or other shadow libraries, or if they were referenced in Wikipedia.

We used descriptive statistics to count the prevalence of the number of GPT-fabricated papers across topics and venues and top domains by subject. The pandas software library for the Python programming language (The pandas development team, 2024) was used for this part of the analysis. Based on the multiple coding, paper occurrences were counted in relation to their categories, divided into indexed journals, non-indexed journals, student papers, and working papers. The schemes, subdomains, and subdirectories of the URL strings were filtered out while top-level domains and second-level domains were kept, which led to normalizing domain names. This, in turn, allowed the counting of domain frequencies in the environment and health categories. To distinguish word prominences and meanings in the environment and health-related GPT-fabricated questionable papers, a semantically-aware word cloud visualization was produced through the use of a word rain (Centre for Digital Humanities Uppsala, 2023) for full-text versions of the papers. Font size and y-axis positions indicate word prominences through TF-IDF scores for the environment and health papers (also visualized in a separate bar chart with raw term frequencies in parentheses), and words are positioned along the x-axis to reflect semantic similarity (Skeppstedt et al., 2024), with an English Word2vec skip gram model space (Fares et al., 2017). An English stop word list was used, along with a manually produced list including terms such as “https,” “volume,” or “years.”

• Artificial Intelligence
• / Search engines

Cite this Essay

Haider, J., Söderström, K. R., Ekström, B., & Rödl, M. (2024). GPT-fabricated scientific papers on Google Scholar: Key features, spread, and implications for preempting evidence manipulation. Harvard Kennedy School (HKS) Misinformation Review . https://doi.org/10.37016/mr-2020-156

• / Appendix B

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This research has been supported by Mistra, the Swedish Foundation for Strategic Environmental Research, through the research program Mistra Environmental Communication (Haider, Ekström, Rödl) and the Marcus and Amalia Wallenberg Foundation [2020.0004] (Söderström).

Competing Interests

The authors declare no competing interests.

The research described in this article was carried out under Swedish legislation. According to the relevant EU and Swedish legislation (2003:460) on the ethical review of research involving humans (“Ethical Review Act”), the research reported on here is not subject to authorization by the Swedish Ethical Review Authority (“etikprövningsmyndigheten”) (SRC, 2017).

This is an open access article distributed under the terms of the Creative Commons Attribution License , which permits unrestricted use, distribution, and reproduction in any medium, provided that the original author and source are properly credited.

Data Availability

All data needed to replicate this study are available at the Harvard Dataverse: https://doi.org/10.7910/DVN/WUVD8X

Acknowledgements

The authors wish to thank two anonymous reviewers for their valuable comments on the article manuscript as well as the editorial group of Harvard Kennedy School (HKS) Misinformation Review for their thoughtful feedback and input.

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• Citing sources

Citation Styles Guide | Examples for All Major Styles

Published on June 24, 2022 by Jack Caulfield . Revised on November 7, 2022.

A citation style is a set of guidelines on how to cite sources in your academic writing . You always need a citation whenever you quote , paraphrase , or summarize a source to avoid plagiarism . How you present these citations depends on the style you follow. Scribbr’s citation generator can help!

Different styles are set by different universities, academic associations, and publishers, often published in an official handbook with in-depth instructions and examples.

There are many different citation styles, but they typically use one of three basic approaches: parenthetical citations , numerical citations, or note citations.

Parenthetical citations

• Chicago (Turabian) author-date

CSE name-year

Numerical citations

CSE citation-name or citation-sequence

Note citations

• Chicago (Turabian) notes and bibliography

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Table of contents

Types of citation: parenthetical, note, numerical, which citation style should i use, parenthetical citation styles, numerical citation styles, note citation styles, frequently asked questions about citation styles.

The clearest identifying characteristic of any citation style is how the citations in the text are presented. There are three main approaches:

• Parenthetical citations: You include identifying details of the source in parentheses in the text—usually the author’s last name and the publication date, plus a page number if relevant ( author-date ). Sometimes the publication date is omitted ( author-page ).
• Numerical citations: You include a number in brackets or in superscript, which corresponds to an entry in your numbered reference list.
• Note citations: You include a full citation in a footnote or endnote, which is indicated in the text with a superscript number or symbol.

Citation styles also differ in terms of how you format the reference list or bibliography entries themselves (e.g., capitalization, order of information, use of italics). And many style guides also provide guidance on more general issues like text formatting, punctuation, and numbers.

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In most cases, your university, department, or instructor will tell you which citation style you need to follow in your writing. If you’re not sure, it’s best to consult your institution’s guidelines or ask someone. If you’re submitting to a journal, they will usually require a specific style.

Sometimes, the choice of citation style may be left up to you. In those cases, you can base your decision on which citation styles are commonly used in your field. Try reading other articles from your discipline to see how they cite their sources, or consult the table below.

The American Anthropological Association (AAA) recommends citing your sources using Chicago author-date style . AAA style doesn’t have its own separate rules. This style is used in the field of anthropology.

APA Style is defined by the 7th edition of the Publication Manual of the American Psychological Association . It was designed for use in psychology, but today it’s widely used across various disciplines, especially in the social sciences.

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The citation style of the American Political Science Association (APSA) is used mainly in the field of political science.

The citation style of the American Sociological Association (ASA) is used primarily in the discipline of sociology.

Chicago author-date

Chicago author-date style is one of the two citation styles presented in the Chicago Manual of Style (17th edition). It’s used mainly in the sciences and social sciences.

The citation style of the Council of Science Editors (CSE) is used in various scientific disciplines. It includes multiple options for citing your sources, including the name-year system.

Harvard style is often used in the field of economics. It is also very widely used across disciplines in UK universities. There are various versions of Harvard style defined by different universities—it’s not a style with one definitive style guide.

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MLA style is the official style of the Modern Language Association, defined in the MLA Handbook (9th edition). It’s widely used across various humanities disciplines. Unlike most parenthetical citation styles, it’s author-page rather than author-date.

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The American Chemical Society (ACS) provides guidelines for a citation style using numbers in superscript or italics in the text, corresponding to entries in a numbered reference list at the end. It is used in chemistry.

The American Medical Association ( AMA ) provides guidelines for a numerical citation style using superscript numbers in the text, which correspond to entries in a numbered reference list. It is used in the field of medicine.

CSE style includes multiple options for citing your sources, including the citation-name and citation-sequence systems. Your references are listed alphabetically in the citation-name system; in the citation-sequence system, they appear in the order in which you cited them.

The Institute of Electrical and Electronics Engineers ( IEEE ) provides guidelines for citing your sources with IEEE in-text citations that consist of numbers enclosed in brackets, corresponding to entries in a numbered reference list. This style is used in various engineering and IT disciplines.

The National Library of Medicine (NLM) citation style is defined in Citing Medicine: The NLM Style Guide for Authors, Editors, and Publishers (2nd edition).

Vancouver style is also used in various medical disciplines. As with Harvard style, a lot of institutions and publications have their own versions of Vancouver—it doesn’t have one fixed style guide.

The Bluebook: A Uniform System of Citation is the main style guide for legal citations in the US. It’s widely used in law, and also when legal materials need to be cited in other disciplines.

Chicago notes and bibliography

Chicago notes and bibliography is one of the two citation styles presented in the Chicago Manual of Style (17th edition). It’s used mainly in the humanities.

The Oxford University Standard for the Citation of Legal Authorities ( OSCOLA ) is the main legal citation style in the UK (similar to Bluebook for the US).

There are many different citation styles used across different academic disciplines, but they fall into three basic approaches to citation:

• Parenthetical citations : Including identifying details of the source in parentheses —usually the author’s last name and the publication date, plus a page number if available ( author-date ). The publication date is occasionally omitted ( author-page ).
• Numerical citations: Including a number in brackets or superscript, corresponding to an entry in your numbered reference list.
• Note citations: Including a full citation in a footnote or endnote , which is indicated in the text with a superscript number or symbol.

Check if your university or course guidelines specify which citation style to use. If the choice is left up to you, consider which style is most commonly used in your field.

• APA Style is the most popular citation style, widely used in the social and behavioral sciences.
• MLA style is the second most popular, used mainly in the humanities.
• Chicago notes and bibliography style is also popular in the humanities, especially history.
• Chicago author-date style tends to be used in the sciences.

Other more specialized styles exist for certain fields, such as Bluebook and OSCOLA for law.

The most important thing is to choose one style and use it consistently throughout your text.

A scientific citation style is a system of source citation that is used in scientific disciplines. Some commonly used scientific citation styles are:

• Chicago author-date , CSE , and Harvard , used across various sciences
• ACS , used in chemistry
• AMA , NLM , and Vancouver , used in medicine and related disciplines
• AAA , APA , and ASA , commonly used in the social sciences

APA format is widely used by professionals, researchers, and students in the social and behavioral sciences, including fields like education, psychology, and business.

Be sure to check the guidelines of your university or the journal you want to be published in to double-check which style you should be using.

MLA Style  is the second most used citation style (after APA ). It is mainly used by students and researchers in humanities fields such as literature, languages, and philosophy.

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Caulfield, J. (2022, November 07). Citation Styles Guide | Examples for All Major Styles. Scribbr. Retrieved September 9, 2024, from https://www.scribbr.com/citing-sources/citation-styles/

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