In-text citation in Chicago Author-Date Style uses the author's last name, publication date, and page number of the source (when applicable). Use a comma between the year and page numbers. Separate multiple authors' names with a comma. Place citations before a punctuation mark whenever possible.
When the author's name appears in the text, you can omit it from the parenthetical citation.
(Gilman 1980, 399)
2 or 3 authors
(Merk, Fogg, and Snowe 1983, 47)
4 or more authors
(Plaumann et al. 1999, 262)
(National Technographic 2005)
Access Date: Use only if publication dates are unavailable for electronic works, or in the case of web sites.
Authors: Invert the 1st author's name in the reference list (Lastname, Firstname); do not invert subsequent authors' names. Use “and,” not an ampersand, for multi-author entries. For 2-3 authors, write out all names. For 4-10 authors, write out all names in the reference list but use only the 1st author’s name plus “et al.” in parenthetical citations.
Date: If publication date of a printed work cannot be determined, use abbreviation “n.d.” (no date).
DOIs: Use DOIs instead of URLs whenever possible. In references, put the word doi in lowercase followed by a colon (with no space after).
Indentation: Format first line of each reference entry flush left and indent subsequent lines 0.5” from the left margin to form a hanging indent.
No Author: When a source has no identifiable author, cite it by its title, both on the references page and in shortened form (up to 4 keywords from title) in in-text citations.
Order: Alphabetize references according to the 1st word in each entry: usually the last name of the 1st author of a work, if the source has no author, use the first word or words in the title, omitting the first the, an, and a.
Pagination: Include a page range for articles. Don't repeat the hundreds digit in a page range if it doesn't change from the beginning to the end of the range (e.g.,152-67). If you can't name a specific page number when called for, use section (sec.), equation (eq.), volume (vol.), or note (n.).
Publishers: Write out publishers’ names in full.
References TItle: Label the first page of the source list “References,” without bolding, italics, or quotation marks.
Spacing: Leave two blank lines between the title and the first entry. Single-space reference entries internally; use a double-space between entries.
Titles: Titles mentioned in the text or references are capitalized “headline style.” Italicize book and periodical titles. Enclose article and chapter titles in quotation marks.
URLs: Use only when DOI is unavailable.
Volume, Issue, Pages: Volume number follows journal title with no punctuation and no italics. Issue number (if it is given) or the month/season of the issue is enclosed in parentheses, followed by a colon and then page information. For notes, page number(s) refer only to material referenced in that section; the bibliography includes the first and last pages of articles. Examples: 4 (2):331-49 ; 112 (April): 643-47.