Last copies: What's at risk?

Last copies are a class of unique library materials that are at risk and warrant consideration for long-term preservation. WorldCat, the OCLC Online Computer Library Center, Inc. bibliographic database, contains 24 million records for items held by only a single OCLC member library. The characteristics of these unique materials are not well understood. This study proposes a conceptual model derived from the examination of materials held exclusively by Vanderbilt University Libraries. The libraries hold approximately 1.5 million items in WorldCat. Of these, more than 23,000 are held only by Vanderbilt University Libraries. The bibliographic records and, in selected cases, the items themselves, were examined to determine characteristics and to identify the items whose content is at risk. The last copies at Vanderbilt University Libraries fell into four broad categories: (1) unidentified manuscripts, (2) last copies, (3) duplicate records, and (4) last expressions.