Chicago-style source citations come in two varieties: (1) notes and bibliography and (2) author-date. If you already know which system to use, follow one of the links above to see sample citations for a variety of common sources. If you are unsure about which system to use, or how the two systems are related, read on.
In the notes and bibliography system, sources are cited in numbered footnotes or endnotes. Each note corresponds to a raised (superscript) number in the text. Sources are also usually listed in a separate bibliography. The notes and bibliography system, Chicago’s oldest and most flexible, can accommodate a wide variety of sources, including unusual ones that don’t fit neatly into the author-date system. For this reason, it is preferred by many working in the humanities, including literature, history, and the arts.
In the author-date system, sources are briefly cited in the text, usually in parentheses, by author’s last name and year of publication. Each in-text citation matches up with an entry in a reference list, where full bibliographic information is provided. Because it credits researchers by name directly in the text while at the same time emphasizing the date of each source, the author-date system is preferred by many in the sciences and social sciences.
Aside from the use of numbered notes versus parenthetical references in the text, the two systems share the same style for authors’ names, titles of works, and other cited components. Follow the links at the top of this page to see examples of some of the more common source types cited in both systems.
Most authors choose the system used by others in their field or required by their publisher. Students should check with their instructor before deciding which system to use.
For a more comprehensive overview of Chicago’s two systems of source citation, see chapter 13 of The Chicago Manual of Style. For many more examples organized by type of source, consult chapter 14.
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