by Yale University Library
Guidelines for “special situations for variant copies of multi-part monographs” and for added variant copies.
Available at: https://web.library.yale.edu/cataloging/workflow/added-copy-or-new-record-books/variant-copies
Archived with Internet Archive (2018-12-07): https://web.archive.org/web/20181207162323/https://web.library.yale.edu/cataloging/workflow/added-copy-or-new-record-books/variant-copies