Citation, Documentation of Sources

Q. In CMOS 14.160, you recommend citing reflowable electronic text using “a chapter number or a section heading or other such milepost in lieu of a page or location number.” Should the section heading be labeled “section” to show that it is intended as a location?

A. The key word is “under,” and in a book with chapters it’s helpful to add a chapter number in addition to a section title. For example, the EPUB edition of Matthew Shindell’s For the Love of Mars could be cited in a note as follows:

1. Matthew Shindell, For the Love of Mars: A Human History of the Red Planet (Chicago: University of Chicago Press, 2023), chap. 4, under “The Nineteenth-Century Cosmic Epic,” EPUB.

2. Shindell, Mars, chap. 5, under “Mars after Detente.”

But it’s usually better for your readers if you cite specific pages in books (partly because books are so long). If you have the option of consulting a print or PDF edition of a book, do so, and then cite by page number.