A collaborative effort of the Networked Digital Library of Theses and Dissertations (NDLTD), OCLC, VTLS, and Scirus, the NDLTD Union Catalog contains more than one million records of electronic theses and dissertations. For students and researchers, the Union Catalog makes individual collections of NDLTD member institutions and consortia appear as one seamless digital library of electronic theses and dissertations.

Indice SBN is the union catalog of the Italian libraries that have joined the National Library Service. The National Library Service (SBN) is the library network in Italy created by Ministry for Cultural and Environmental Asset with the cooperation of the regions and universities. Libraries participating in the SBN project are more than 1000, among others the National Central Libraries in Rome and Florence, as well as state, city, university and academic libraries. Indice SBN provides access to bibliographic records which are periodically downloaded from the SBN Modern Books and Periodicals, Older Books and Music databases.

In addition to the 75.000 prints belonging to the basic content, VD16 comprises a supplement of more than 25.000 new titles. New titles are added continuously through acquisitions by the Bayerische Staatsbibliothek for the Collection of German Prints, as well as through data provided by national and foreign libraries.