This catalogue records information in e-journals, e-books, databases, and printed material about themes in the field of the international law. Especially, a large part of the print collection of the Peace Palace Library is searchable through this catalogue. This collection consists of books and materials since 1913.

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.