Q. I’m looking for a source for guidelines on what to display on a website when only one source is referenced in an online article. Is it okay to still put 1? I have previously been told by college professors and professional colleagues to substitute an asterisk instead.
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).