Bureau Herkomst Gezocht's researchers primarily use the Stichting Nederlandsch Kunstbezit (1945-1951) archive. The research method has been standardised in order to fully utilise this archive. The archival documents which definitely have to be examined in order to arrive at the correct provenance data have been determined. A file has been drawn up per art object which consists of basic documentation, correspondence, photographic material and other archival documents. The basic documentation consists of the Netherlands Institute for Cultural Heritage inventory card, a notification (forms with which after the war citizens reported artworks missing), a SNK inventory card and a copy from the SNK inventory ledger. The research into paintings and drawings involves the systematic searching in the (auction)catalogues and photo collection of the Netherlands Institute for Art History. Other relevant archive materials, such as data from the administration of the 'robber bank' Lippmann, Rosenthal & Co, is added to the file and digitally processed. Furthermore, new archives can yield interesting data which sheds new light on the provenance of an art object.