Chicago Manual of Style Author-Date Citations and Bibliographic References

This tutorial is a quick guide to Chicago Manual of Style (CMS) author-date citations and bibliographic references. This style is of special note to geographers because it is the citation style used by the Annals of the Association of American Geographers, the flagship publication of the premier professional society of geographers in the United States.

Note that CMS author-date style, which is commonly used in the sciences and social sciences, is different from CMS notes and bibliography style, which is more-commonly used in the humanities.


Author-date citations flow in the text and cite literature using the last name(s) of the author(s) and the year of publication. The general formats of CMS author-date in-text citations are as follows:

If there are one to three authors, cite them all with last names.

If there are four or more authors, cite the first author's last name, followed by the Latin abbreviation et al.


Natural-gas-fired power plants are less-expensive and more thermodynamically efficient compared to other types of fossil-fueled power plants (Afework et al. 2018).

Vogel (2017) identified 55 chemicals released during the fracking process that are associated with increased cancer risk.

Yang et al. (2000) found increased lung cancer mortality associated with petroleum refineries, but no association with abnormal birth sex ratios.

Shand (1993, 148) notes that although Kant was sociable and enjoyed the company of women, he was the stereotypical "self-contained philosophical speculator" and never married.

CMS author-date citation format is of special interest to geographers because it is the citation style used in The Annals of the Association of American Geographers, the flagship publication of the premier professional society of geographers in the United States (Minn 2018).

Bibliographic References

All in-text citations need to have a matching reference entry in the bibliography, which is usually at the end of the document.

The general format for CMS author-date bibliographic references is:

Lastname, Firstname. Year. "Title." Media.

Where multiple authors are given the first name should be given as last, first with subsequent names first last.

Lastname, Firstname, Firstname Lastname, and Firstname Lastname. Year. "Title." Media.

Web Pages

If the web page does not list an author, the name of the organization that publishes the page should be used as the author

If the web page does not list the date when the content was last updated, use the current year

If the website is associated with a magazine, list the name of the magazine and the publication month and day

Because websites often change frequently, an accessed date is usually given with the URL


Afework, Bethel, Jordan Hanania, James Jenden, Kailyn Stenhouse, and Jason Donev. 2018. "Energy education: Natural gas power plant." Accessed 26 October 2018.

American Stroke Association. 2018. "About Stroke." Accessed 30 September 2018.

Bradley, Ryan. 2018. "Why bigger planes mean cramped quarters." Popular Science, 22 August. Accessed 11 November 2018.

Cook, Lindsey. 2015. "You're Most Likely to Die From Cancer in 1 of These States." US News and World Report, 15 October. Accessed 27 October 2018.

Minn, Michael. 2018. "Chicago Manual of Style Author-Date Citations and Bibliographic References." Accessed 16 December 2018.

Wikipedia. 2018. "Stroke Belt." Accessed 30 September 2018.


References to articles from journals need to include the volume number, the issue number within that volume, and the range of pages occupied by that article.

The general format for journal articles is:

Author. Year. "Title." Journal Volume (Issue): Pages.

Although not a formal part of CMS author-date style, providing a URL to the web page for the article can be helpful for readers.

Some journals provide a digital object identifier (DOI) link that is intended to be a permanent web address. Because such links are permanent, no accessed date is necessary.


Minn, Michael. 2013. "The Political Economy of High Speed Rail in the United States." Mobilities 8 (2): 185-200.

Vogel, Lauren. 2017. "Fracking tied to cancer-causing chemicals." Canadian Medical Association Journal 189 (2): E94 - E95. Accessed 26 October 2018.

Yang, Chun-Yuh, Bi-Hua Cheng, Te-Yao Hsu, Shang-Shyue Tsai, Chung-Feng Hung, and Trong-Neng Wu. 2000. "Female Lung Cancer Mortality and Sex Ratios at Birth near a Petroleum Refinery Plant." Environmental Research 83 (1): 33-40.


Books sources are listed with a city of publication and the name of the publisher.


Shand, John. 1993. "Philosophy and Philosophers: An Introduction to Western Philosophy." Montreal: McGill-Queen's University Press.

McLafferty, Sara and Ellen Cromley. 2012. "GIS and Public Health," second edition. New York: Guilford Press.

Data Sources

Although CMS author-date citations are intended for citation of textual information, they can also be used to cite data sources.


Centers for Disease Control and Prevention and The National Cancer Institute (CDC). 2018. "State Cancer Profiles, Incidence Rate Report for United States by County, 2010-2014." Accessed 15 May 2018.

US Energy Information Administration. 2018. "U.S. Power Plants." Accessed May 15, 2018.