Q. I find ISBNs extremely useful when trying to locate copies of books of interest, especially when searching for secondhand copies of out-of-print books, for requesting books on interlibrary loan, and for disambiguating common names or titles. I’m writing a literature review in the form of an annotated bibliography and would like to include ISBNs in the entries for those books that have them, as a convenience and finding aid for readers. I can’t find any guidance for inclusion of ISBNs in Chicago-style footnotes or bibliography entries, even as an optional item. Can you provide a recommended template or example of placement and formatting?
A. Sure. Here’s how we’d recommend adding ISBNs to the bibliography entries for three different editions of Daniel James Brown’s bestselling book about a rowing team’s quest for Olympic gold at the 1936 Berlin Olympics (listed here in chronological order, from the 2013 Viking hardcover to the 2023 Penguin Books movie tie-in edition):
Brown, Daniel James. The Boys in the Boat. Viking, 2013. ISBN 978-0-670-02581-7.
Brown, Daniel James. The Boys in the Boat. Penguin Books, 2014. ISBN 978-0-143-12547-1.
Brown, Daniel James. The Boys in the Boat. Movie tie-in ed. Penguin Books, 2023. ISBN 978-0-593-51230-2.
In general, an ISBN or other optional information may be added to an entry in a bibliography when needed, following the period at the end of the other citation data. But if you need to include an ISBN within a note, we’d suggest adding it in parentheses, as part of the facts of publication:
1. Daniel James Brown, The Boys in the Boat, movie tie-in ed. (Penguin Books, 2023; ISBN 978-0-593-51230-2), 33–34.
The hyphens in the ISBN, which are optional, will help those who need to manually copy or type the number. For more on ISBNs and how they work, start with CMOS 1.36 and these FAQs from ISBN.org.