Restrict these to their prescribed use, i.e. two or more works "contained in the physical item at the time of publishing, release, issue, or execution" (cf. MARC21 documentation, 501 field); for works bound together subsequent to publication, place this information in a 562 note with accompanying 977 fields in holdings. (see Section V.3.).
For volumes made up of previously published materials reissued, usually with a collective title page but not always (often referred to as nonce collections), create a single bibliographic record for the collection (with a contents note). Curatorial requests to create individual analytical records should be discussed with the Head of Rare Book Section.