The project is investigating the approach in acquisition after 1945. Even in the post-war period books by persecuted persons found their way into the ULB holdings, especially through antiquarian bookshops, private individuals or the Allies' collection points. This is called “secondary loot”.

The reason why the Nazi period is not the focus of the investigation is due to the history of the ULB. The former State Library suffered considerable losses in a bombing raid on 11 September 1944, and tried to fill the resulting gaps with low-cost acquisitions in the post-war period. As random samples showed, this allowed large quantities of Nazi loot to end up in the library. It can be assumed that most of the looted books acquired before 1945 were destroyed in the bombing raid. One exception is forbidden literature that was secreted at the time, which was preserved and is therefore included in the investigation.

The research project is based on the holdings of the former State Library, which was re-formed after its destruction in 1945-1949. This applies to the shelf marks 45/ to 47/ and 49/ set up as numerus currens, a total of about 40,000 volumes. The books are inspected directly on the shelf (autopsy method) and searched for provenance features of the previous owners, such as ex libris, stamps and the like. Other sources are the library accession registers, which contain information on suppliers (not always reliable), archival sources and relevant databases.