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Chicago Style Guide: Author-Date (Parenthetical) System

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Scope: This guide is designed to help researchers learn how to cite sources using the Chicago Manual of Style. This system, also known as Turabian, is often used in history, the humanitites, and the arts. This guide is not meant to be a comprehensive list of all sources you may encounter. For more information and examples, refer to the The Chicago Manual of Style or Kate Turabian's Manual for Writers of Research Papers, Theses, and Dissertations: Chicago Style for Students and Researchers. Both manuals are available at the McKeldin Reference Desk (Z253 .U69 2010 and LB2369.T8 2007, respectively) as well as several other campus libraries. Both may also be purchased through the University Book Store or commercial vendors


Table of Contents


Why cite?


In researched writing, proper citation increases your credibility and allows readers to locate your sources; conversely, a failure to document your sources is plagiarism, a violation of the University of Maryland's Code of Academic Integrity with serious consequences.

Avoid plagiarism by gathering the information you need to create a citation when you first find each of your sources; don't wait until you begin writing the paper.


Overview of the Chicago/Turabian documentation system

The Chicago system (also known as the Turabian system) allows for two different systems of documentation. The notes system is suggested for use in the humanities, art, and history, and uses footnotes (notes at the bottom of the page) to document sources. The in-text parenthetical system (known as the author-date system) is suggested for use in the physical, natural, and social sciences and uses endnotes (notes at the end of the paper on a separate sheet) to document sources.

This guide outlines the author-date system. For more information on using the notes system, see the Chicago Style Guide: Notes System page.

What distinguishes the author-date system from the notes system is that the author-date system inserts minimal source information directly into the text itself, surrounded by parentheses, and follows up with the rest of the source information in a list of references at the end of the paper. Imagine that you're writing a paper on the ideal politician and are quoting a particular author's ideas about desirable qualities in a politician. An exerpt from a sentence in the text of a paper written using the author-date would look like this:

While some assert that the essential qualities a politician must possess
are, "passion, a feeling of responsibility, and a sense of proportion"
(Weber 1946, 33), others think that ... 

The entry in the list of references would look like this:

Weber, Max. 1946. Politics as a Vocation. In  Essays in Sociology, ed.
     H.H. Garth and C. W. Mills, 26-45. New York: Macmillian.


Common Reference List Examples


This guide shows the most common sources appearing in research bibliographies. For more specific needs, see the The Chicago Manual of Style.


Book by a single author

In the note, the author's name will appear in the usual order; in the bibliography it will be given with the last name first.

Bagby, John W. Cyberlaw Handbook for E-Commerce. New York: Harcourt
     Brace, 2003.

Book with multiple authors

If the book has two or three authors, include all authors in the note and the bibliography. If the book has more than three authors, include all authors in the bibliography but only the first author followed by "and others" or "et al." in the note.

Smith, John, Janice Brown, Chris W. Enkunde, and Lois Denmark. The History
     of the World Wide Web. 2nd ed. Chicago: University of Chicago Press,

Book with editors

Baumer, David L., Julius Poindexter, and Janice Brown, eds. Cyberlaw
     and E-Commerce. Boston: McGraw Hill, 2002.

Chapter in an edited book

Heller, Chris, and Andrea Gottlieb. "Gender Roles in Ethiopian Culture." In
      Gender in Cross-Cultural Perspective, edited by Sherry Collier, 45-56.
     Louisville, KY: Pilgrim Press, 2001.



Journal article (print)

Include the volume and issue number (if available). Give the range of page numbers on which the article appears in the bibliography and the specific page reference in the note (unless you are referring to the article as a whole).

James, Earl W.T., and Lucy Danker. "Obesity in American School Children: An
     Epidemic." Journal of Nursing 389, no. 12 (2000): 399-405.

Journal article retrieved online

Include a URL for articles retrieved online or through an academic database such as EBSCOhost. Include page numbers for the print version if they are given.

Stem, Caroline J., James P. Lassoie, David R. Lee, and David J. Dessler.
     "How 'Eco' is Ecotourism? A Comparative Case Study of Ecotourism in
     Costa Rica." Journal of Sustainable Tourism 11, no. 4 (2003):

You do not need to include the access date unless your instructor requires it or the information is very time-sensitive. If you do to include the date, put it in parentheses at the end of the citation:

Stem, Caroline J., James P. Lassoie, David R. Lee, and David J. Dessler.
     "How 'Eco' is Ecotourism? A Comparative Case Study of Ecotourism in
     Costa Rica." Journal of Sustainable Tourism 11, no. 4
     (2003): 322-348. (accessed March 6, 2005).  

Magazine article

Monthly magazines are usually cited by date only, even if volume and issue information is available.

Elliott, Michael. "Gypsy Foklore Revisited."  Smithsonian, March
     2004, 23-29.

For a magazine article accessed online, include the URL for the article or database from which it was retrieved. Again, volume and issue information is typically not included. Include the date the material was accessed only if your instructor requires it or the information is very time-sensitive.

Roman, Monica. "Son of Nafta?"  Business Week, December 12, 2003.

Newspaper article

Chicago style recommends not including page numbers, as they may change between editions, though it may be helpful to include a section number or name and the particular edition consulted.

Edward Epstein, "It's That Time Again: Lawmakers Revisit Daylight Saving,"
     San Francisco Chronicle, April 9, 2005, final edition.

If you access the article online through the newspaper's website, include the URL. If the URL for the specific article stops working, use the newspaper's homepage instead (e.g.,

Lewin, Tamar, "College Enrollment Set Record in 2008," New York Times,
    October 29, 2009.

If you access the article through an academic database, include the home URL for that database service:

Daniel Howden, "Polio at Mecca Sparks Fear for Muslim Thousands,"
    Independent (London), February 12, 2005, first edition.


Other Sources

Unpublished dissertation

Fitzpatrick, Kerry J. "Effects of Mowing on the Selection of Raptor Foraging
     Habitat." PhD diss., University of Maryland, 2003.

Government document

This format may be used for reports, bulletins, circulars, and miscellaneous material issued by executive departments, bureaus, and agencies.

U.S. Department of Agriculture. Irrigation: A National Research Plan.
     Washington, DC: GPO, 2001.

If the government document is accessed online, include the URL and date it was accessed:

U.S. Department of Justice. Bureau of Justice Statistics. Analysis of
     Crime Patterns 1990-2000 by Shirley Marimer. Washington, DC: GPO, 2002. (accessed April 14, 2005).

Personal communication

Personal communication such as e-mails, telephone calls, or unpublished interviews are usually cited in the text or a note, but rarely appear in the bibliography. For example:

"In an e-mail message received by the author on December, 12, 2203, Sheila
McCarthy stated that ..." 

Websites and Blogs

Include as much of the following information as you can: author, title of the specific article, title of the site, sponsor of the site, and URL. Chicago style only recommends including the access date if the material is especially time-sensitive (or if your instructor requires it). If no author's name is given, use the sponsor of the site in the author's position.

Sullivan, Danny. "Boolean Searching."  Search Engine Watch.

Freakomics Blog;"Carrots and Sticks has landed," blog entry
    by Ian Ayres, September 22, 2010

Audiovisual Materials

Audiovisual materials are treated much like books, with the addition of the medium consulted (e.g., VHS, DVD).

Power! 1967-1968. VHS. Directed by Louis Massiah and Terry Kay
     Rockefeller. Boston, MA: Public Broadcasting System Video, 1999.

Search Smarter, Search Faster, YouTube video, 6:54, posted by
     uniofsydney, May 28,2008,


How to construct an in-text parenthetical reference

The author-date citation in the text must correspond exactly to its full citation in the reference list.

  • Basic form. Include the author's last name and year of publication.
       (Cox 1997)
  • Two authors with the same last name. Add a first initial to distinguish between the two.
       (M. Cox 1997)
  • Citation of a specific page or section. Insert a comma after the date and then give page number. Always include page number for direct quotations.
       (Cox 1997, 21)
  • Two publications by the same author in the same year. Use "a" and "b" to differentiate between the two.
       (Cox 1997a) and (Cox 1997b)
  • Two or three authors. Include all names in the citation.
       (Cox, Cunningham, and Hatleberg 1997)
  • More than three authors. Include the first name, followed by "et al." (meaning "and others").
       (Cox et al. 1997)
  • Multiple references in the same citation. Separate the citations with semicolons.
       (Cox 1997; Cunningham 1996; Hatleberg 1996)