Citation, Documentation of Sources

Q. I am editing a paper in which the bibliography has a few entries with many coauthors—e.g., over fifty. The author has listed all the names. Surely, when the list of authors goes beyond twenty-five lines—in one case, over a page—I can use et al.? If that’s the case, how many do I list before using et al.? Thanks!

A. If you are using notes-bibliography style, please see CMOS 14.76: “For works with more than ten authors—more common in the natural sciences—Chicago recommends the policy followed by the American Naturalist (see bibliog. 5): only the first seven should be listed in the bibliography, followed by et al. (Where space is limited, the policy of the American Medical Association may be followed: up to six authors’ names are listed; if there are more than six, only the first three are listed, followed by et al.).” If you are using author-date style, list all the authors (CMOS 15.9).