Q. When citing an endnote, should the page number be the page the note callout appears on or the page where the endnote is at the end of the book (24n5 vs. 385n5)?
A. Footnote or endnote, you’re citing the note itself, not its reference number in the text. For an endnote, the page number to cite is the one at the end of the book where the note can be found (or 385n5 in your example).
This does mean that readers who follow the citation to its source will need to track down the note reference in the text if they want to see the context for that note, but endnotes are almost always less user-friendly than footnotes (unless the notes are linked, as in an ebook).
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. I’m in the middle of working with a client on a white paper that has citations to articles found on government agency websites (e.g., Centers for Disease Control and Prevention, National Institutes of Health, Office of Disease Prevention). The writing is completed, we’re in the layout/production stage, and while checking links and confirming URLs in the endnotes, we’re finding that articles and pages that had been referenced in our endnotes have now been removed from the government websites in accordance with the administration’s recent orders. How do we reference reports and articles that are significant but have been removed?
A. Whenever you find a dead link (or a link that works but points to a different version of the cited content), you have a few options, which are the same regardless of why the link no longer works as intended:
- If the cited page can’t be found anywhere, and the author didn’t save a copy, then you can either (a) add “(page no longer available)” or similar wording after the URL (as shown at CMOS 14.104), or (b) ask the author to revise the text and citation to fix the problem (perhaps by referring to and citing a different document). Option a should be used only as a last resort.
- If the author did save a copy, you can add that fact to the notice suggested for option a above: “(page no longer available; copy of original in author’s possession).” Option 1b may still be preferable unless the cited document is crucial to the author’s paper.
- If you can track down an archived version of the page—for example, at the Internet Archive’s Wayback Machine—you can cite that (after making sure that any text that relies on that page, including any direct quotations, remains accurate).
Option 3 is usually best, assuming the content has been archived in a way that allows others to consult it. For example, consider the following URL, which as of March 4, 2025, results in a “Page Not Found” notice:
https://www.cdc.gov/healthcommunication/Health_Equity.html
If you paste that URL into the Wayback Machine, you’ll find dozens of archived versions (or snapshots) dating back to August 25, 2021. Here’s how we’d cite one of those versions, following the recommendations at CMOS 14.104 (and using the “last reviewed” date reported at the bottom of that page in lieu of a publication date; see CMOS 13.16):
1. “Health Equity Guiding Principles for Inclusive Communication,” Gateway to Health Communication, CDC, last reviewed August 11, 2023, archived July 24, 2024, at https://web.archive.org/web/20240724170713/https://www.cdc.gov/healthcommunication/Health_Equity.html.
If you can’t find the page at the Wayback Machine or anywhere else, you’re back to options 1 and 2 at the beginning of this answer.
Links break for many reasons, but there are some basic precautions that authors can take to prevent the scenario described in the question above from happening in the first place:
- First, always save a copy of any web page (including any PDFs) that you consult as you do your research (e.g., as a screenshot or as an HTML or PDF file). Zotero and other citation managers can help with this task. See also CMOS 13.13 and 13.17.
- Second, don’t assume that a page will have been archived by someone else (as was the case for the CDC.gov URL in the example above). Instead, create your own archived version if you can—for example, by pasting the URL into the Save Page Now feature at the Wayback Machine. This won’t always be an option (some content will be blocked from being archived), but at least you’ll have your own personal copy to point to (see previous bullet) if anyone challenges your research.
Copyeditors can help by alerting authors to any page that may need to be archived or saved in one of the ways described above—and by editing citations accordingly. That should keep everyone, including readers, on the same page.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. I am wondering how best to cite, within one chapter of a multiauthor book, other chapters from the same volume. I am accustomed to simply adding “(see chapter X)” to the text, but one author is pushing back and wants to see them in the reference list. We are using author-date style.
A. Chapters in multiauthor books are likely to be consulted separately (and are sometimes offered for individual download or sale), so listing other chapters from that same book in the reference list at the end of your own chapter wouldn’t be the worst idea. But you should still let readers know that the chapter you’re citing is in the same book.
We’d suggest adding this information to the author-date reference for that chapter in your text—for example, like this: “(Smith 2025, in this volume).” The corresponding entry in your reference list would include the book’s title (per CMOS 13.109), so a similar comment shouldn’t be needed there:
Smith, Jane. 2025. “Chapter Title.” In Title of Book, edited by Joe Anyone. Publisher details.
If you cite more than a few chapters from your book, you may want to use a shortened form for the book: “In Anyone, Title of Book.” But even if you do that, you shouldn’t need to add a separate entry in the reference list for the book as a whole, the identity of which should be obvious to anyone who is already reading something from that book. For some additional considerations, see CMOS 14.10, under “author-date.”
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. CMOS 13.128 shows how to use author-date citations in a footnote, but what about an informational footnote like, “The history of exclusion of Chinese people in the United States has been highly researched. To begin, see . . .”? Should the parentheses around the citations be removed, as in “To begin, see Chan 1991, Lee 2003, and Kurashige 2016”? Otherwise, it might seem as though the citations are substantiating the statement, rather than being offered as suggested reading.
A. In Chicago style, the “see” in “see Chan” means that you’re referring to a work rather than a person, and the year would retain parentheses whether in the text or in a note: “To begin, see Chan (1991), Lee (2003), and Kurashige (2016).” If you’re instead referring to the author in terms of the work, the wording would need to make that clear: “See the earlier efforts by Chan (1991) to digitize the archival records.”
Parentheses for the year are omitted only when the citation is itself in parentheses, in which case semicolons rather than commas separate the sources, as in “(to begin, see Chan 1991; Lee 2003; Kurashige 2016).” But if your parenthetical reference is to an author rather than a work, the year would get square brackets: “(See the earlier efforts by Chan [1991] to digitize the archival records.)” See CMOS 13.122 and 13.124.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
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.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. Hello, Chicago doesn’t seem to have an example of how to cite a contribution to a new edition of a book. Should the edition number follow a period or comma in the reference list entry below? Though my example is in Chicago 17 style, the question is still relevant for Chicago 18 style, so I would appreciate your guidance. Thanks!
Rothbard, Murray N. 2006. “The Libertarian Heritage: The American Revolution and Classical Liberalism.” In For a New Liberty: The Libertarian Manifesto, 1–23. 2nd ed. Auburn, AL: Ludwig von Mises Institute.
A. The best place for an edition number for a book is usually just after the title. When it’s part of an “In . . .” statement (as in your example), it follows a comma. As of the 18th edition, Chicago no longer requires a page range for a chapter or other contribution to a book or a place of publication, so your author-date entry would look like this:
Rothbard, Murray N. 2006. “The Libertarian Heritage: The American Revolution and Classical Liberalism.” In For a New Liberty: The Libertarian Manifesto, 2nd ed. Ludwig von Mises Institute.
(If you were following CMOS 17, the edition number would precede the page range: “. . . Manifesto, 2nd ed., 1–23. . . .”) In a reference list entry for the book as a whole, the edition number would follow a period:
Rothbard, Murray N. 2006. For a New Liberty: The Libertarian Manifesto. 2nd ed. Ludwig von Mises Institute.
Bibliography entries would follow the same pattern (except for the placement of the year of publication; see CMOS 14.1).
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. Why is ibid. preferable to id.? The meaning is essentially the same and id. is more succinct, and it is used extensively in legal citation without any apparent confusion or misunderstanding.
A. What you say is true. But because id. (idem, the same) is used mainly in legal citations whereas ibid. (ibidem, in the same place) has long been preferred in history and most other academic disciplines, ibid. is much more well known than id. Whether ibid. also benefits from not looking like id (the complement to the ego and superego) is anyone’s guess.
For more on ibid. and id. (including Chicago’s preference for shortened citations over either of those abbreviations), start with CMOS 13.38.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. How would you cite a website home page in a bibliography? Would the page title be “Home Page” (in quotes) or just a descriptive “Home page” (no quotes)? Or the title of the website? Or something else entirely?
A. A home page is almost never titled “Home Page,” so a description is your best option (though you can leave that out if it’s obvious from the URL and the other information in your citation). Note also that a home page isn’t normally a source that you’d list in a bibliography; consider limiting your citation to a mention in either the text or a note (though we’ll show the form for a bibliography entry here).
Wherever you cite it, you should save a version of the page as it existed when you consulted it. Unlike a published article or other content that may be available from a home page, a home page itself is designed to change over time (i.e., as a site adds content or to keep up with new software, or both).
If it is important to share this version with your readers, use the Internet Archive’s Wayback Machine or a similar service to create a public link and cite that version as follows:
University of Chicago Press (home page). Archived November 27, 2024. https://web.archive.org/web/20241127140410/https://press.uchicago.edu/index.html.
That’s the page at https://press.uchicago.edu/index.html as it existed on November 27 at four minutes and ten seconds after two in the afternoon UTC (the string of numbers in the middle of the URL; that link points to the page as saved using the Wayback Machine’s Save Page Now feature). If you do not cite an archived version, you will need to include an access date. For more details and examples, see CMOS 14.104. For the meaning of UTC (Coordinated Universal Time), see 10.47.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. How should one cite a published book that is in an archival (personal papers) collection? The most important element of the book is not the text but the annotations added by the person whose collection the book is in. Thanks!
A. Cite the book like any other book; then cite the archive according to the advice and examples in CMOS 14.119–29, prefacing this information with “in” if it immediately follows the book citation (cf. CMOS 13.25).
The goal is to make it clear which book you’re citing and where the copy that has the annotations can be found. The annotations themselves can be discussed anywhere—in your text, in your notes, or in an addendum to a bibliography entry for the book (see CMOS 13.68, item 3)—and you can cite specific page numbers where applicable. But the annotations wouldn’t be cited as a separate entity.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]
Q. If an author insists on using a widely attributed quote whose source cannot be confirmed, how should I cite it? Should I cite it at all? Or should I simply note in the running text that the quote is “widely attributed to such and such”?
A. Your last idea is the best one. In general, if the source of a quotation can’t be confirmed, this fact should be stated in the text that introduces it instead of being relegated to a note, where readers might miss it. The phrase “widely attributed” should make it clear that the attribution isn’t definitive; however, if the author can provide one or more sources that back up this claim, those could be (and in an academic work should be) provided in a note.
[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]