The Chicago Manual of Style (CMS) provides two primary systems for in-text citations: the author-date system and the notes-bibliography system. Each serves different academic disciplines and purposes. This page covers both methods and provides examples for each.
Author-Date System
The author-date system is typically used in the sciences and social sciences. In this system, in-text citations include the author’s last name and the year of publication, with a page number added if specific information is cited.
Basic Format
- General: (Author’s Last Name Year)
- With Page Number: (Author’s Last Name Year, Page Number)
Examples
- Paraphrasing:
- Climate change significantly impacts marine biodiversity (Smith 2020).
- Smith (2020) discusses the significant impacts of climate change on marine biodiversity.
- Direct Quotation:
- “Marine ecosystems are particularly vulnerable to the effects of climate change” (Smith 2020, 45).
- Smith (2020, 45) states that “marine ecosystems are particularly vulnerable to the effects of climate change.”
- Multiple Authors:
- Two Authors: (Brown and Smith 2017)
- Three or More Authors: (Williams et al. 2016)
Multiple Works by the Same Author
If citing multiple works by the same author from the same year, distinguish them with letters (e.g., 2020a, 2020b).
- Example:
- (Smith 2020a, 2020b)
Notes-Bibliography System
The notes-bibliography system is commonly used in the humanities, especially in history, literature, and the arts. In this system, citations are provided in footnotes or endnotes.
Basic Format
- In-Text: Superscript number corresponding to a footnote or endnote.
- Footnote/Endnote: Full bibliographic details for the first citation, shortened form for subsequent citations.
Examples
- In-Text Example:
- The impact of climate change on marine biodiversity has been well documented.¹
- Footnote/Endnote Example:
- First Citation: ¹ John Smith, The Impact of Climate Change on Marine Life (New York: Marine Publishing, 2020), 45.
- Subsequent Citation: ² Smith, Impact of Climate Change, 47.
Shortened Citations
For subsequent citations of the same source, use a shortened form including the author’s last name, a shortened title of the work, and the page number.
- Example:
- First Citation: John Smith, The Impact of Climate Change on Marine Life (New York: Marine Publishing, 2020), 45.
- Subsequent Citations: Smith, Impact of Climate Change, 47.
Multiple Authors
- Two Authors:
- Bibliography Entry: Brown, Lisa, and Mark Smith. Sustainable Marine Practices. Boston: Environmental Press, 2017.
- First Footnote: Lisa Brown and Mark Smith, Sustainable Marine Practices (Boston: Environmental Press, 2017), 23.
- Subsequent Footnote: Brown and Smith, Sustainable Marine Practices, 25.
- Three or More Authors:
- Bibliography Entry: Williams, Richard, Sandra Lee, and Thomas Green. “Marine Conservation Strategies.” Environmental Studies Quarterly 22, no. 3 (2016): 200-220.
- First Footnote: Richard Williams, Sandra Lee, and Thomas Green, “Marine Conservation Strategies,” Environmental Studies Quarterly 22, no. 3 (2016): 205.
- Subsequent Footnote: Williams, Lee, and Green, “Marine Conservation Strategies,” 207.
Ibid.
For consecutive citations of the same source, the term “ibid.” (short for the Latin “ibidem,” meaning “in the same place”) can be used.
- Example:
- First Footnote: John Smith, The Impact of Climate Change on Marine Life (New York: Marine Publishing, 2020), 45.
- Subsequent Footnote: Ibid., 47.
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