Citation, Documentation of Sources

Q. In cases where a single short quotation stands completely on its own (such as in the front matter of a book or in a social media post), I generally see it attributed using a dash and the person’s name (“—Albert Einstein,” for example). Is this format accepted by Chicago, or is it strictly informal? Also, is it an em dash, en dash, or hyphen?

A. The use of an em dash with the source of an epigraph indeed fits with Chicago style. Please see CMOS 13.36 for an example.