http://www.loc.gov/mods/v3 http://www.loc.gov/standards/mods/v3/mods-3-2.xsd
Number your catalogs and provide the index cards
"This system contemplates the serial numbering of all trade catalogs, pamphlets, circulars, bulletins, and reference data when they are published; and uniform, printed, index cards to be furnished with the catalog"--Page 3.