The author-date system is used by many in the physical, natural, and social sciences and is recommended by Chicago for works in those areas. Sources are cited in the text, usually in parentheses, by the author’s last (family) name, the publication date of the work cited, and a page number if needed. Full details appear in the reference list—usually titled “References” or “Works Cited”—in which the year of publication appears immediately after the author’s name. This arrangement makes it easy to follow a text citation to the corresponding full source in the reference list. (In electronic formats, text citations may be linked to their corresponding reference list entries.)
Grazer, Brian, and Charles Fishman. 2015. A Curious Mind: The Secret to a Bigger Life. New York: Simon & Schuster.
Smith, Zadie. 2016. Swing Time. New York: Penguin Press.
(Grazer and Fishman 2015, 12)
(Smith 2016, 315–16)
For more examples, see 15.40–45 in The Chicago Manual of Style.
Chapter or other part of an edited book:
In the reference list, include the page range for the chapter or part. In the text, cite specific pages.
Thoreau, Henry David. 2016. “Walking.” In The Making of the American Essay, edited by John D’Agata, 167–95. Minneapolis: Graywolf Press.
(Thoreau 2016, 177–78)
D’Agata, John, ed. 2016. The Making of the American Essay. Minneapolis: Graywolf Press.
(D’Agata 2016, 177–78)
For more details, see 15.36 and 15.42 in The Chicago Manual of Style.
Lahiri, Jhumpa. 2016. In Other Words. Translated by Ann Goldstein. New York: Alfred A. Knopf.
(Lahiri 2016, 146)
For books consulted online, include a URL or the name of the database in the reference list entry. For other types of e-books, name the format. If no fixed page numbers are available, cite a section title or a chapter or other number in the text, if any (or simply omit).
Austen, Jane. 2007. Pride and Prejudice. New York: Penguin Classics. Kindle.
Borel, Brooke. 2016. The Chicago Guide to Fact-Checking. Chicago: University of Chicago Press. ProQuest Ebrary.
Kurland, Philip B., and Ralph Lerner, eds. 1987. The Founders’ Constitution. Chicago: University of Chicago Press. http://press-pubs.uchicago.edu/founders/.
Melville, Herman. 1851. Moby-Dick; or, The Whale. New York: Harper & Brothers. http://mel.hofstra.edu/moby-dick-the-whale-proofs.html.
(Austen 2007, chap. 3)
(Borel 2016, 92)
(Kurland and Lerner 1987, chap. 10, doc. 19)
(Melville 1851, 627)
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 or the name of the database in the reference list entry. Many journal articles list a DOI (Digital Object Identifier). A DOI forms a permanent URL that begins https://doi.org/. This URL is preferable to the URL that appears in your browser’s address bar.
Keng, Shao-Hsun, Chun-Hung Lin, and Peter F. Orazem. 2017. “Expanding College Access in Taiwan, 1978–2014: Effects on Graduate Quality and Income Inequality.” Journal of Human Capital 11, no. 1 (Spring): 1–34. https://doi.org/10.1086/690235.
LaSalle, Peter. 2017. “Conundrum: A Story about Reading.” New England Review 38 (1): 95–109. Project MUSE.
Satterfield, Susan. 2016. “Livy and the Pax Deum.” Classical Philology 111, no. 2 (April): 165–76.
(Keng, Lin, and Orazem 2017, 9–10)
(LaSalle 2017, 95)
(Satterfield 2016, 170)
Journal articles with multiple authors:
If there are four or more authors, list up to ten in the reference list; in the text, list only the first, followed by et al. (“and others”). For more than ten authors (not shown here), list the first seven in the reference list, followed by et al.
Bay, Rachael A., Noah Rose, Rowan Barrett, Louis Bernatchez, Cameron K. Ghalambor, Jesse R. Lasky, Rachel B. Brem, Stephen R. Palumbi, and Peter Ralph. 2017. “Predicting Responses to Contemporary Environmental Change Using Evolutionary Response Architectures.” American Naturalist 189, no. 5 (May): 463–73. https://doi.org/10.1086/691233.
(Bay et al. 2017, 465)
For more examples, see 15.46–49 in The Chicago Manual of Style.
News or magazine article:
Articles from newspapers or news sites, magazines, blogs, and the like are cited similarly. In the reference list, it can be helpful to repeat the year with sources that are cited also by month and day. Page numbers, if any, can be cited in the text but are omitted from a reference list entry. If you consulted the article online, include a URL or the name of the database.
Manjoo, Farhad. 2017. “Snap Makes a Bet on the Cultural Supremacy of the Camera.” New York Times, March 8, 2017. https://www.nytimes.com/2017/03/08/technology/snap-makes-a-bet-on-the-cultural-supremacy-of-the-camera.html.
Mead, Rebecca. 2017. “The Prophet of Dystopia.” New Yorker, April 17, 2017.
Pai, Tanya. 2017. “The Squishy, Sugary History of Peeps.” Vox, April 11, 2017. http://www.vox.com/culture/2017/4/11/15209084/peeps-easter.
Pegoraro, Rob. 2007. “Apple’s iPhone Is Sleek, Smart and Simple.” Washington Post, July 5, 2007. LexisNexis Academic.
(Mead 2017, 43)
Readers’ comments are cited in the text but omitted from a reference list.
(Eduardo B [Los Angeles], March 9, 2017, comment on Manjoo 2017)
For more examples, see 15.49 (newspapers and magazines) and 15.51 (blogs) in The Chicago Manual of Style.
Kakutani, Michiko. 2016. “Friendship Takes a Path That Diverges.” Review of Swing Time, by Zadie Smith. New York Times, November 7, 2016.
Stamper, Kory. 2017. “From ‘F-Bomb’ to ‘Photobomb,’ How the Dictionary Keeps Up with English.” Interview by Terry Gross. Fresh Air, NPR, April 19, 2017. Audio, 35:25. http://www.npr.org/2017/04/19/524618639/from-f-bomb-to-photobomb-how-the-dictionary-keeps-up-with-english.
Thesis or dissertation:
Rutz, Cynthia Lillian. 2013. “King Lear and Its Folktale Analogues.” PhD diss., University of Chicago.
(Rutz 2013, 99–100)
It is often sufficient simply to describe web pages and other website content in the text (“As of May 1, 2017, Yale’s home page listed . . .”). If a more formal citation is needed, it may be styled like the examples below. For a source that 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.
Bouman, Katie. 2016. “How to Take a Picture of a Black Hole.” Filmed November 2016 at TEDxBeaconStreet, Brookline, MA. Video, 12:51. https://www.ted.com/talks/katie_bouman_what_does_a_black_hole_look_like.
Yale University. n.d. “About Yale: Yale Facts.” Accessed May 1, 2017. https://www.yale.edu/about-yale/yale-facts.
(Yale University, n.d.)
For more examples, see 15.50–52 in The Chicago Manual of Style. For multimedia, including live performances, see 15.57.
Social media content:
Citations of content shared through 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 160 characters of the post. Comments are cited in reference to the original post.
Conan O’Brien’s tweet was characteristically deadpan: “In honor of Earth Day, I’m recycling my tweets” (@ConanOBrien, April 22, 2015).
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.
Souza, Pete (@petesouza). 2016. “President Obama bids farewell to President Xi of China at the conclusion of the Nuclear Security Summit.” Instagram photo, April 1, 2016. https://www.instagram.com/p/BDrmfXTtNCt/.
(Chicago Manual of Style 2015)
(Michele Truty, April 17, 2015, 1:09 p.m., comment on Chicago Manual of Style 2015)
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.
(Sam Gomez, Facebook message to author, August 1, 2017)
When using parenthetical documentation for in-text citations, remember that sources cited in the text must point to specific sources on the References page.