University of New England - Innovation for a Healthier Planet
UNE Library Services > Research Skills > Citations > Chicago Style Guides > Author-Date System

Research Skills

Author-Date System

The Chicago Style Author-Date (AD) system cites sources in the text by author’s last name and year of publication.

In-Text Citations

An in-text citation is a brief reference within your text that indicates the source you consulted. It should properly attribute any ideas, paraphrases, or direct quotations and directs readers to an entry in a bibliography section at the end of the paper where a complete reference is provided.

Summarizing

Include an in-text citation whenever you summarize or paraphrase the ideas of another author. Use only the surname of the author followed by the year of publication.

Example: (Winkleman 2020).

Multiple Authors

When citing multiple authors, separate names with a comma and use “and” before the final name.

Example: (Winkleman and Kurtine 2019) or (Winkelman, Smith, and Kurtine 2019).

Author’s name in the sentence

If using the author’s name in the sentence, only include the year in parentheses.

Example: Winkleman (2020, 134) cited political indifference as the problem.

Specific place in Text

Include page, chapter, section, or paragraph numbers when quoting or referring to a specific place in the text.

Example: (Winkleman 2020, 134).

Bibliographies

General Rules

  • In Chicago style, the list of works cited is called “Bibliography.”
  • Alphabetize the references by author last name or first word of the citation.
  • For more than ten authors, list the first seven in the reference list, followed by “et al.”
  • Use hanging indentation.

Formatting References

  • Italicize the titles of books and journals. Place the titles of articles, chapters, poems, etc. in quotation marks.
  • Capitalize all words article, chapter and book titles and subtitles. Capitalize journal titles in the same way as the journal does.
  • Cite a section title, chapter, other number in the text, if no fixed page numbers are available. You may also simply omit.
  • If there is no publication date listed, use n.d. (no date) and include an access date.
  • For multiple authors, list the first author as last name, first name. All subsequent names should be listed as first name last name. 

Online Sources

References to online sources contain the same elements in the same order as do references to print sources, with the addition of retrieval information so that a reader can locate the source.

  • Include a URL or the name of the database in the reference list entry for books consulted online.
  • Include a URL or the name of the database in the reference list entry for online articles. Many journal articles list a DOI (Digital Object Identifier). A DOI forms a permanent URL that begins https://doi.org/. A DOI is preferable to the URL that appears in your browser’s address bar and should be used when available.

Examples

Articles

Journal Article

Turner, Thomas L. 2020. “The Marine Sponge Hymeniacidon perlevis is a Globally-Distributed Exotic Species.” Aquatic Invasions: 15 (4): 542-561. https://www.reabic.net/aquaticinvasions/2020/AI_2020_Turner.pdf.

Newspaper or Magazine Article

Hoey, Dennis. 2021. “Rare Yellow Lobster Donated to UNE’s Marine Science Center.” Portland Press Herald, February 5, 2021. https://www.pressherald.com/2021/02/04/rare-yellow-lobster-donated-to-unes-marine-science-center.

Books

Book by One Author (Print Version)

Klinenberg, Eric. 2018. A Palaces for the People: How Social Infrastructure Can Help Fight Inequality, Polarization, and the Decline of Civic Life. Curious Mind: The Secret to a Bigger Life. New York: Broadway Books.

eBook

Brown, Brene. 2012. Daring Greatly: How the Courage to be Vulnerable Transforms the Way We Live, Love, Parent and Lead. New York: Gotham Books. ProQuest Ebrary.

Book by Two or More Authors (Print Version)

Bernstein, Carl, and Bob Woodward. 1974.  All the President’s Men. New York: Simon & Schuster.

Chapter in an Edited Book (Print Version)

Smith, John. 2022. “The Impact of Climate Change on Biodiversity.” In Environmental Challenges in the 21st Century, edited by Laura Johnson and Michael Brown, 45-67. Chicago: University of Chicago Press.  

Webpages

University of New England Library Services. 2019. “Copyright & Fair Use.” Accessed May 1, 2019. https://www.library.une.edu.

Note: If the year of publication is not available use n.d. for no date.

Film or Television

Tyson, Neil deGrasse, presenter. 2014. Cosmos: A Spacetime Odyssey. Beverly Hills: CA: Twentieth Century Fox. DVD Video.  

Blog Post

Males, Jamie. 2022. “Warming Coral Reefs in the Past, Present, and Future: An Interview with PLOS Climate Authors.” Latitude (blog). March 9, 2022. https://latitude.plos.org/2022/03/warming-reefs/. 

Podcast

Radke, Heather and Matt Kielty. 2023. “Man Against Horse.” Radiolab, July 7, 2023. Podcast, MP3 audio, 59:47. https://radiolab.org/podcast/man-against-horse-2307.  

Images

Images are not typically included in a reference list in Chicago Author-Date style. However, if you include an image in your text, caption it with: 

Creator, date of creation, title of work, and where it is located.  

Thesis or Dissertation

Brill-Lee, Rachel. 2022. “Examining Middle School Core Teacher Knowledge And Practices In Stem Education.” EdD diss., University of New England.

Legal Case

Chicago does not currently have a format for citing legal cases in the bibliography, they recommend only citing in text.

Personal Communication

Personal communications such as letters and emails are not typically included in the bibliography in Chicago Style. In-text they should appear as:

(Steven Miller, Email to the author, July 19, 2023.) 

Questions & Help

If you have questions on this, or another topic, contact a librarian for help!