Chicago B: Author-Date

Chicago reference style is available in two variants:

The below examples illustrate the author-date system. Each example of a reference list entry is accompanied by an example of a corresponding in-text citation. For more details and many more examples, see chapters 13 and 14 of The Chicago Manual of Style. For examples of the same citations using the notes and bibliography system, see Chicago A Notes and Bibliography.

About the author-date style

In the author-date system, sources are briefly cited in the text, usually in parentheses, by author’s last name and year of publication. Each in-text citation matches up with an entry in a reference list, where full bibliographic information is provided. Because it credits researchers by name directly in the text while at the same time emphasizing the date of each source, the author-date system is preferred by many in the sciences and social sciences.

Aside from the use of numbered notes (Chicago A) versus parenthetical references in the text (Chicago B), the two systems share the same style for authors’ names, titles of works, and other cited components.

Specifics for using Chicago B for in-text references

  • When using secondary references, name both sources in-text: Johnson and Peters’ studies (1939, cited in Wagner 1982, 207)
  • To distinguish multiple publications by the same author published the same year, write a, b, c, etc. after the year: Hansen (1988a) and Hansen (1988b) in both the citation and reference list.
  • When a work has no identifiable author, write the title.
  • Publications with many authors who are cited more than once:
    • 2 or 3 authors: write both authors’ names every time you cite them. Example: (Furseth and Everett 1997), (Reve, Lensberg and Grønhaug 1992)
    • 4 or more authors: only write the surname of the first author followed by et al. Example: Cheng et al. (2004)

Book

Reference list entries (in alphabetical order)

Note that the place of publication is no longer required.

The place of pubication is no longer required in book citations for books published sincde 1900. If for any reason a place is included (authors should resist doing so, but the occasional reference may benefit from readers knowing its place of origin), use the first-listed city on the title page or, if no city is listed there, refer to the copyright page and cite the city where the publisher’s main editorial offices are located. City names are followed by a colon.

If the city of publication may be unknown to readers or may be confused with another city of the same name, add the abbreviation of the state, province, or (if relevant) country (e.g., Ithaca, NY). City names in languages other than English can usually be recorded as they appear in the source; for contemporary publications, however, a commonly used English name may be used instead (e.g., Mexico City for Ciudad de México or Rome for Roma).

Binder, Amy J., and Jeffrey L. Kidder. 2022. The Channels of Student Activism: How the Left and Right Are Winning (and Losing) in Campus Politics Today. University of Chicago Press.

Yu, Charles. 2020. Interior Chinatown. Pantheon Books.

In-text citations

(Binder and Kidder 2022, 117–18)

(Yu 2020, 45)

Chapter or other part of an edited book

The page range for a chapter in a book is no longer required in reference list entries. In the text, cite specific pages as applicable.

Reference list entry

Doyle, Kathleen. 2023. “The Queen Mary Psalter.” In The Book by Design: The Remarkable Story of the World’s Greatest Invention, edited by P. J. M. Marks and Stephen Parkin. University of Chicago Press.

In-text citation

(Doyle 2023, 64)

In some cases, you may want to cite the collection as a whole instead:

Reference list entry

Marks, P. J. M., and Stephen Parkin, eds. 2023. The Book by Design: The Remarkable Story of the World’s Greatest Invention. University of Chicago Press.

In-text citation

(Marks and Parkin 2023)

Translated book

Reference list entry

In the following example, note the absence of a comma after “Liu” in the author’s name, which follows Eastern order (family name first) rather than Western order (family name last). See CMOS 13.75 for more details.

Liu Xinwu. 2021. The Wedding Party. Translated by Jeremy Tiang. Amazon Crossing.

In-text citation

(Liu 2021, 279)

Book consulted in an electronic format

URL or database

To cite a book consulted online, include either a URL or the name of the database in the reference list entry. For downloadable ebook formats, name the format; if no fixed page numbers are available, cite a section title or a chapter or other number in the text (or simply omit). For citing a place rather than a publisher for books published before 1900 (as in the Moby-Dick example below).

Reference list entries (in alphabetical order)

Borel, Brooke. 2023. The Chicago Guide to Fact-Checking. 2nd ed. University of Chicago Press. EBSCOhost.

Kurland, Philip B., and Ralph Lerner, eds. 1987. The Founders’ Constitution. University of Chicago Press. https://press-pubs.uchicago.edu/founders/.

Melville, Herman. 1851. Moby-Dick; or, The Whale. New York. https://melville.electroniclibrary.org/moby-dick-side-by-side.

Roy, Arundhati. 2008. The God of Small Things. Random House. Kindle.

In-text citations

(Borel 2023, 92)

(Kurland and Lerner 1987, chap. 10, doc. 19)

(Melville 1851, 627)

(Roy 2008, chap. 6)

Journal article

URL or DOI

Journal articles are usually cited by volume and issue number. In the reference list, include the page range for the whole article. In the text, cite specific page numbers. For articles consulted online, include a URL (preferably one based on a DOI) in the reference list entry; alternatively, list the name of the database.

Reference list entries (in alphabetical order)

Dittmar, Emily L., and Douglas W. Schemske. 2023. “Temporal Variation in Selection Influences Microgeographic Local Adaptation.” American Naturalist 202 (4): 471–85. https://doi.org/10.1086/725865.

Hebert, B. T. 1925. “The Island of Bolsö: A Study of Norwegian Life.” Sociological Review 17 (4): 307–13. EBSCOhost.

Kwon, Hyeyoung. 2022. “Inclusion Work: Children of Immigrants Claiming Membership in Everyday Life.” American Journal of Sociology 127 (6): 1818–59. https://doi.org/10.1086/720277.

Lindquist, Benjamin. 2023. “The Art of Text-to-Speech.” Critical Inquiry 50 (2): 225–51. https://doi.org/10.1086/727651.

In-text citations

(Dittmar and Schemske 2023, 480)

(Hebert 1925, 310)

(Kwon 2022, 1842–43)

(Lindquist 2023, 230)

Many authors

Journal articles often list many authors, especially in the sciences. For works by two authors, list both in the reference list and the text (as in the Dittmar and Schemske example above). For three or more authors, list up to six in the reference list; for more than six authors, list the first three, followed by “et al.” (“and others”). In the text, list only the first, followed by “et al.” Note that the Dror example below (which credits eighteen authors) includes an article ID in place of a page range.

Reference list entry

Dror, Amiel A., Nicole Morozov, Amani Daoud, et al. 2022. “Pre-Infection 25-Hydroxyvitamin D3 Levels and Association with Severity of COVID-19 Illness.” PLOS ONE 17 (2): e0263069. https://doi.org/10.1371/journal.pone.0263069.

In-text citation

(Dror et al. 2022, 10–11)

News or magazine article

Articles from newspapers or news sites, magazines, blogs, and the like are cited similarly. Page numbers, if any, can be cited in the text but are omitted from a reference list entry. For articles consulted online, include a URL or the name of the database.

Reference list entries (in alphabetical order)

Blum, Dani. 2023. “Are Flax Seeds All That?” New York Times, December 13. https://www.nytimes.com/2023/12/13/well/eat/flax-seeds-benefits.html.

Klein, Elana. 2023. “Meet Flip, the Viral Video App Giving Away Free Stuff.” Wired, December 21. https://www.wired.com/story/flip-viral-video-app-shopping-free-stuff/.

Mead, Rebecca. 2023. “Terms of Aggrievement.” New Yorker, December 18. Pegoraro, Rob. 2007. “Apple’s iPhone Is Sleek, Smart and Simple.” Washington Post, July 5. LexisNexis Academic.

In-text citation

(Blum 2023)

(Klein 2023)

(Mead 2023, 21)

(Pegoraro 2007)

Readers’ comments are cited in the text but omitted from a reference list:

In-text citation

(Michelle [Reno], December 15, 2023, comment on Blum 2023)

Book review

Reference list entry

Jacobs, Alexandra. 2023. “The Muchness of Madonna.” Review of Madonna: A Rebel Life, by Mary Gabriel. New York Times, October 8.

In-text citation

(Jacobs 2023)

Interview

Interviews are usually cited under the name of the interviewee rather than the interviewer.

Reference list entry

Buolamwini, Joy. 2023. “ ‘If You Have a Face, You Have a Place in the Conversation About AI,’ Expert Says.” Interview by Tonya Mosley. Fresh Air, NPR, November 28. Audio, 37:58. https://www.npr.org/2023/11/28/1215529902/unmasking-ai-facial-recognition-technology-joy-buolamwini.

In-text citation

(Buolamwini 2023)

Thesis or dissertation

For dissertations consulted via ProQuest; include the identification number in parenthesis.

Reference list entry

Blajer de la Garza, Yuna. 2019. “A House Is Not a Home: Citizenship and Belonging in Contemporary Democracies.” PhD diss., University of Chicago. ProQuest (13865986).

In-text citation

(Blajer de la Garza 2019, 66–67)

Web page

It is often sufficient simply to describe web pages and other website content in the text (“As of November 15, 2023, Google’s privacy policy stated . . .”). If a more formal citation is needed, it may be styled like the examples below.

Reference list entries (in alphabetical order)

Google. 2023. “Privacy Policy.” Privacy & Terms. Effective November 15. https://policies.google.com/privacy.

Wikimedia Foundation. 2023. “Wikipedia: Manual of Style.” Last modified December 19, at 21:54 (UTC). https://en.wikipedia.org/wiki/Wikipedia:Manual_of_Style.

In-text citations

(Google 2023)

(Wikimedia Foundation 2022)

No date

If a source does not list a date of publication or revision, use n.d. (for “no date”) in place of the year and include an access date. Alternatively, if a publicly available archive of the content has been saved using the Internet Archive’s Wayback Machine or similar service, the link for that version may be cited.

Yale University. n.d. “About Yale: Yale Facts.” Accessed March 8, 2022. https://www.yale.edu/about-yale/yale-facts.

or

Yale University. n.d. “About Yale: Yale Facts.” Archived March 8, 2022, at https://web.archive.org/web/20220308143337/https://www.yale.edu/about-yale/yale-facts.

Social media content

Citations of content posted to social media can usually be limited to the text (as in the first example below). If a more formal citation is needed, a reference list entry may be appropriate. In place of a title, quote up to the first 280 characters of the post. Comments are cited in reference to the original post.

Text

The Instagram post included a photo of the president delivering a eulogy at the National Cathedral and referred to O’Connor as “gracious and principled” (@potus, December 19, 2023).

Reference list entries (in alphabetical order)

Chicago Manual of Style. 2015. “Is the world ready for singular they? We thought so back in 1993.” Facebook, April 17, 2015. https://www.facebook.com/ChicagoManual/posts/10152906193679151.

NASA Webb Telescope (@NASAWebb). 2022. “👀 Sneak a peek at the deepest & sharpest infrared image of the early universe ever taken—all in a day’s work for the Webb telescope. (Literally, capturing it took less than a day!).” Twitter (now X), July 11. https://twitter.com/NASAWebb/status/1546621080298835970.

In-text citations

(Chicago Manual of Style 2015)

(NASA Webb Telescope 2022)

(Michele Truty, April 17, 2015, 1:09 p.m., comment on Chicago Manual of Style 2015)

Video or podcast

Unless it is clear from context, “video” or the like may be specified in the reference list.

Reference list entries (in alphabetical order)

Cowan, Vaitea. 2022. “How Green Hydrogen Could End the Fossil Fuel Era.” TED Talk, Vancouver, BC, April. Video, 9 min., 15 sec. https://www.ted.com/talks/vaitea_cowan_how_green_hydrogen_could_end_the_fossil_fuel_era.

Ober, Lauren, host. 2022. The Loudest Girl in the World. Season 1, episode 2, “Goodbye, Routine; Hello, Meltdown!” Pushkin Industries, September 13. Podcast, 41 min., 37 sec. https://www.pushkin.fm/podcasts/loudest-girl-in-the-world.

Oliver, Eric. 2022. “Why So Many Americans Believe in So Many ‘Crazy’ Things.” Moderated by Andrew McCall. Virtual lecture, February 23. Posted March 21, 2022, by University of Chicago. YouTube, 1:01:45. https://youtu.be/hfq7AnCF5bg.

In-text citations

(Cowan 2022, at 6:09–17)

(Ober 2022)

(Oliver 2022)

Personal communication

Personal communications, including email and text messages and direct messages sent through social media, are usually cited in the text only; they are rarely included in a reference list.

In-text citation

(Sam Gomez, Facebook direct message to author, August 1, 2024)

ChatGPT and artificial intelligence

The Chicago styles recommends that references to ChatGPT and other similar services are treated the same way as personal communication. Personal communication and text generated by large language models cannot be reproduced or found, and they should therefore not appear in the reference list.

Reports etc.

Flyers, rapports, pamphlets and other free publications are sorted as books. Author and publisher data may not fit the usual pattern, but sufficient information should be provided to identify the document.

Laws

Chicago recommends The Blue Book: A Uniform System of Citation, published by the Harvard Law Review Association, to cite legal and public documents, statutes, and other government documents. Laws are usually not placed in the bibliography, only in the footnote.

Art

Information about paintings, photographs, sculptures, or other art is usually presented in the text instead of citations or reference list. If a note or some other bibliographic information is necessary, write the artist’s name, the art title (in italics) and the date/year, followed by information about the art and placement of the art. Provide the URL for the artwork if published online.

Guide

See also the guide at NTNU Oppaveskriving

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