The Mozart collection of the former Preußische Staatsbibliothek (Prussian state library) is the largest and most important collection of the composer's original manuscripts and transcripts in the world. Since the end of the Second World War, part of the collection has been located in the university library in Krakow. For the microfiche edition, both parts of the holdings have been filmed (the autographs in color) for the first time. In addition to listing the microfiche, the Catalogue contains a list of the signatures filmed in Berlin and Krakow and an index of the reproduced works in compliance with the 'Köchelverzeichnis'. The introduction provides insights into the history of the holdings.