Citation, Documentation of Sources

Q. I am citing a letter from a volume of documents that was once part of a manuscript collection at an archive. I have a photocopy of the letter, made twenty-five years ago when the volume was at the archive, but the volume has since been stolen. How do I cite the letter?

A. You could cite the document and add “The volume has since been lost” or “No longer available.” Be sure to add the word photocopy to your citation (see CMOS 14.218). You don’t want readers to think you’re the perp who took the original!