Citation, Documentation of Sources

Q. We are currently revising the references of a book chapter and have come across the following problem: Two sources of the same year have the identical first seven authors, and we don’t know how to differentiate them in the text (authors, year). In this case a and b are not applicable, because starting with the eighth author, the authors are not the same. Should we list all eight names in both cases?

A. I’m afraid you’re stuck with naming all the authors:

(Grumpy, Doc, Happy, Sleepy, Bashful, Sneezy, Dopey, and Snow 2008)

(Grumpy, Doc, Happy, Sleepy, Bashful, Sneezy, Dopey, and Queen 2008)

An alternative is to annotate the reference list with something like “In text, referred to as Grumpy et al. [1] 2008.” Putting [1] after the author instead of a after the date indicates that Grumpy et al. [1] and Grumpy et al. [2] are different author groups, whereas 2008a and 2008b indicate different works of the same author group.

[This answer relies on the 17th edition of CMOS (2017) unless otherwise noted.]