Citation, Documentation of Sources

A. In Chicago style, you don’t need to formally cite words written on walls or on labels or cards or elsewhere at an art exhibition. Assuming you’ve supplied full details for the exhibition itself (as in the text or in a note; a bibliography entry is usually unnecessary for live events, though you may list an exhibition catalog there), and assuming also that your text makes it clear that the words are part of that exhibition, you are free to quote section titles and the like without additional citations.

You can also usually discuss specific works of art that are featured in the exhibition without additional citations, as long as you’ve identified these works sufficiently in your text (usually by the name of the creator and a title or description, at the very least). But if you’re a student, check with your instructor, who may expect you to cite individual artworks in your notes or to list them in a bibliography, or both. For examples, see CMOS 14.133. For citing exhibition catalogs, see 14.134. For titles of artworks and exhibitions, see 8.200 and 8.204.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. According to CMOS 13.14, authors don’t need to record DOIs for print resources “unless their publisher or discipline requires it.” And because most readers will assume that a DOI in a citation means you’re referring to something online, it’s generally best not to include one for a work you consulted in print unless you’ve also consulted the online version. (It’s unlikely that a source that’s available only in print will have a DOI.)

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. It’s best not to try to cite separate parts of the same sentence unless it’s perfectly clear what each citation refers to; in your example, we can’t really tell which part is from IMDb and which is from Henry.

But first, there are some other issues that should probably be addressed in your example. We’ve done some digging and determined that your “Henry 1994” almost certainly refers to the following article:

Henry, Matthew. 1994. “The Triumph of Popular Culture: Situation Comedy, Postmodernism and The Simpsons.” Studies in Popular Culture 17 (1): 85–99. http://www.jstor.org/stable/23413793.

Henry, however, does not seem to use the phrase “Simpsons craze” in that article (or the word “craze” by itself)—not on page 87 or elsewhere. Perhaps you’re drawing on this passage from page 87:

The Simpsons was, therefore, inevitable, the next logical step in the blue-collar tradition; its enormous success, however, was quite unexpected.

If that’s the case, then you shouldn’t put “Simpsons craze” in quotation marks. Some people probably referred to that show’s huge popularity in that way, but your source refers to an “enormous success,” not a craze.

Next, if it’s your own claim that the show’s producers could not have predicted the show’s success (something that Henry’s article doesn’t seem to address either), then you need to make that clear.

As for the identity of the producers, The Simpsons has had such a long run that according to IMDb (on its page for the full cast and crew), it’s had more than 150 producers to date. Moreover, the three people you list are credited at IMDb as the show’s creators, not its producers.

Taking all that into account, here’s one way that you might revise the sentence in your question (assuming you have a reason for introducing the creators at this point and that you’ve established elsewhere that you’re talking about the show’s earliest days):

According to Henry (1994), the show’s “enormous success . . . was quite unexpected.” And though Henry does not mention them, the show’s creators—James L. Brooks, Matt Groening, and Sam Simon (IMDb 2026)—were likely among those taken by surprise.

Make sure that “IMDb 2026” in your reference list includes the link to the main page for the show (https://www.imdb.com/title/tt0096697/), where the creators are listed. (But note that at IMDb’s page for the full cast and crew, only Groening gets a creator credit; Brooks and Simon are credited, along with Groening, as developers, one more thing you may want to consider when revising your text.)

Finally, if you were to cite two sources at the end of a sentence, you’d usually do that when both sources supported the same idea, in which case you’d separate them with a semicolon: (IMDb 2026; Henry 1994). See also CMOS 13.116.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. Let’s start with an example of how to cite an unpublished letter in a note (adapted from the examples in CMOS 14.127):

1. George Creel to Colonel House, September 25, 1918, box 31, folder 986, Edward Mandell House Papers, Yale University Library.

That’s American journalist George Creel writing to Edward M. House, an American diplomat and adviser, at that time, to President Woodrow Wilson. The example assumes that House has been identified more fully in the text. (See this article on House in Britannica for the form used in the note; “Colonel” was an honorary rather than a military title.)

A letter is similar to a diary entry, and House’s diaries are also included in the same collection at Yale. House’s diary entry from the same day as the letter could be cited as follows (and note that “Colonel House,” the addressee in the letter from Creel, isn’t used in this context):

2. House, diary, September 25, 1918, Edward Mandell House Papers, Yale University Library, original transcript, ser. 2, vol. 6, https://archives.yale.edu/repositories/12/archival_objects/1748077.

The diary entry, unlike the letter, has been digitized, so we included a URL for the part of the collection where the diary may be found (plus a few more details about the location in the collection). For a diary that isn’t in a public collection, adjust your entry accordingly. Here’s a general-purpose form that can be adapted as needed:

3. So-and-So, diary, February 3, 2026, quoted with the permission of [name of person who owns the diary].

For an alternate date format that may be suitable for works that cite many letters or diary entries, see CMOS 14.122. See also 12.3.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. If there’s a note number 1, readers may expect to find a note number 2 later in the same document. For that reason, using an asterisk instead of a number can make sense when there’s just one note. But there isn’t any general rule that we know of that says you must do this.

Let’s say, for example, that an academic journal uses author-date style supplemented by numbered notes for substantive comments, and that most articles in that journal include more than one note. It would be reasonable in that case, as a matter of consistency across articles, to assign a number even in the case of only one footnote.

So if you have the option of using an asterisk, consider doing so, but it’s not a requirement. For the answer to a similar question about whether to number a single figure in a document, see this Q&A (which links to the seventeenth edition of CMOS but still applies).

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. Normally, you should cite the version you consulted or the best version if you consulted more than one. But Chicago-style source citations can easily accommodate extra details, so if you think it’s important to acknowledge more than one version, you can do that.

To take an example that’s similar to what you’re describing, you could cite the following article as it appeared in a fiftieth-anniversary special issue of the Journal of Literary Semantics and then add info about the original publication (in this case, after the DOI):

Dry, Helen Aristar. “The Movement of Narrative Time.” In “50th Anniversary Issue,” edited by Marina Lambrou, Journal of Literary Semantics 51, no. s1 (2022): 19–53. https://doi.org/10.1515/jls-2021-2043. Facsimile of the article as originally published in Journal of Literary Semantics 12, no. 2 (1983), with the same page numbers.

The wording related to the extra info will depend on the source. In a bibliography or reference list entry, this info follows the period at the end of the main citation; in a note, it can follow a semicolon or start a new sentence (or, if the information is brief, it can go in parentheses).

In an author-date reference list, you could cite both publication dates:

Dry, Helen Aristar. (1983) 2022. “The Movement of Narrative Time.” In “50th Anniversary Issue,” edited by Marina Lambrou, Journal of Literary Semantics 51 (s1): 19–53. https://doi.org/10.1515/jls-2021-2043. Facsimile of the article as originally published in Journal of Literary Semantics 12, no. 2 (1983), with the same page numbers.

In the text, the author-date citation would be “(Dry [1983] 2022).” For more details and examples, see CMOS 14.16 (on reprint editions) and 14.77 (on journal special issues).

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. No formal citation is needed. Instead, just make sure that the name of the app and the entity responsible for it (whether that’s a person or a company) have been clearly and accurately identified in the text as the source for the quotation.

Formal citations (as in a note or in a bibliography or reference list) can usually be limited to sources that readers could consult for themselves if they wanted to. Things that others wouldn’t be able to track down online or anywhere else (not even through a library) can usually be described in the text rather than cited in a footnote or the like.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. Unlike a photographer, the person who creates a screenshot doesn’t usually get credit. But if someone has added annotations or the like that aren’t part of the captured image, that fact should be made clear. For example, the caption and credit for this image—

—might read as follows:

The updated hyphenation guide includes linked cross-references to other terms and sections in the table. Reproduced by permission from The Chicago Manual of Style Online, 18th ed. (University of Chicago Press, 2024), 7.96; arrows added by the author.

See also CMOS 3.21–29 (for captions) and 3.30–38 (for credits).

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. In Chicago and other styles, source citations don’t generally require info about how to access the cited sources. For example, when you cite an article in an academic journal, you don’t need to clarify that readers may need a subscription or library access to read the article (or that they may need to pay a fee to get it).

This approach is necessary because access to most sources is limited in some way (sources don’t magically appear for anyone) and because any restrictions are subject to change without notice.

That said, there’s no rule against including such info in special cases. Here’s how we might add such information to your example, which we’ve adapted here for use with Chicago’s author-date system:

ITU (International Telecommunication Union). n.d. eMIFR (Master International Frequency Register tool). eTerrestrial: An Online Portal for Terrestrial Services. Accessed September 9, 2025. https://​www​.itu​.int​/ITU-R​/eTerrestrial​/eMIFR (requires a TIES [Telecommunication Information Exchange Services] account).

For the use of n.d. (no date) in author-date citations, see CMOS 14.104. For the use of abbreviations in author-date style for an organization as author, see 13.127.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]

A. Yes, we do use those abbreviations; see CMOS 13.117, which shows how to cite a specific page, paragraph, section, volume, or the like in a parenthetical author-date citation in the text. The relevant example is this one:

(Claussen 2015, para. 2.15) or (Claussen 2015, ¶ 2.15)

For two paragraphs, you would use either “paras.” or “¶¶” (for these plural forms, see CMOS 7.15 and 10.49, respectively).

In your example, however, citing “para. 1” or “¶ 1” could be misleading because the paragraphs in the source you quote from aren’t numbered (see “About APA Style” at the APA Style website, archived September 3, 2025, at the Wayback Machine). Instead, you could refer to the first or opening paragraph in your text, but only if that information is relevant. If it’s not, then you don’t need to specify which paragraph; the source is relatively short, and the quoted text provides the key to its location on the page (via the Find tool in any browser). If you still want to add it to your citation, try this: (APA 2025, first para.).

For more on citing website content (including how to cite archived web pages), see CMOS 14.104. For abbreviating the names of organizations listed as authors in author-date citations, see 13.127.

[This answer relies on the 18th edition of CMOS (2024) unless otherwise noted.]