In the online edition, two central sources are linked: the card index from the Archive of the Kunsthistorisches Museum Wien (around 5,900 file cards) and the card index from the Archive of the Federal Monuments Authority Austria (around 5,600 file cards). The annotated catalogue of seizure, also in the KHM archive, serves as an additional source. In 2019 around 400 more file cards from the Archive of Kunsthistorisches Museum Wien were published that had been discovered in the course of inventory taking.

The card indexes record the collections seized from mid-March 1938 by the Nazi regime and deposited from autumn 1938 in the Neue Burg. Most of the individual 12.4 ´ 17.7 cm file cards have a collection abbreviation stamped top left and, directly underneath, a description of the object taken from the seizure catalogue printed in 1939. Some cards have further stamps and handwritten additions indicating where the object was stored in the Central Depot, whether it had been photographed, whether it had been taken for safekeeping in a depository or transferred to another institution.

While the information on the KHM file cards contain next to no information after the year 1942, many BDA cards also have post-war file numbers. Some of the cards have photographs attached, which – like the file cards – have been scanned on both sides. The information on the dispersal of the objects contained in the additional annotations from the seizure catalogue is frequently consistent with the indications on the cards, although there are divergences in some cases.