The first note for each source should include all relevant information about the source: author’s full name, source title, and facts of publication. If you cite the same source again, the note need only include the surname of the author, a shortened form of the title (if more than four words), and page number(s).
If you cite the same source and page number(s) from a single source two or more times consecutively, the corresponding note should use the word “Ibid.,” an abbreviated form of the Latin ibidem, which means “in the same place.” If you use the same source but a different page number, the corresponding note should use “Ibid.” followed by a comma and the new page number(s).
Once you have spelled out a source's information in full in its first note, all subsequent notes take a shorter form.
In addition to the shorter form, the Chicago Manual and Turabian identify rules for using the Latin abbreviation "Ibid." when you refer to one source twice (or more) in a row. (See below).
When citing a source you have already noted in full, use a shorter form so your reader knows what earlier source you are referring to.
If the work and the author remain the same and if you are using only one book or article by that author, simply give the author's last name and page reference:
8. Raúl Sánchez, "Outside the Text: Retheorizing Empiricism and Identity," College English 74 (2012): 243.
Subsequent, (shortened) note:
22. Sánchez, 265.
If you are using two or more works by that author, indicate which of the works you are citing. Use the last name, a shortened title, and page reference.
1. Steven Nadler, A Book Forged in Hell: Spinoza's Scandalous Treatise and the Birth of the Secular Age (Princeton: Princeton University Press, 2011), 8.
23. Nadler, A Book Forged in Hell, 121.
If you use two authors with the same last name, give the full name in the shortened reference.
When a note refers to the same work as the previous note, you can use "ibid." to refer back to the previous source. This is acceptable even if several pages of text separate the two notes.
"Ibid." is an abbreviation of the Latin word ibidem, which means "in the same place."
The abbreviation "Ibid." is followed by a page number if the page from which the second reference is taken is different from the first. If the pages are the same, no number is necessary.
Note that the first source is given a shortened form in note 3, then referred to with "ibid." in notes 4 and 5.
1. Colleen Dunlavy, "Why Did American Businesses Get So Big?" in Major Problems in American Business History, ed. Regina Blaszczyk and Philip Scranton (New York: Houghton-Mifflin, 2006), 260.
2. Steven Nadler, A Book Forged in Hell: Spinoza's Scandalous Treatise and the Birth of the Secular Age (Princeton: Princeton University Press, 2011), 8.
3. Dunlavy, 261.
5. Ibid., 262.