This article aims to provide an update on the status of the restitution efforts and provenance research on the Nazi-looted books acquired by the Berlin City Library in 1943. It includes a brief history of the involved libraries and librarians and summarizes the known sources that are available to date regarding the acquisition. The text at hand also sheds light on how and when the issue of provenance gained importance in the Berlin Central and Regional Library and what steps were taken to develop the co-operative approach to provenance research that is the Looted Cultural Assets database.