Staatsbibliothek zu Berlin – Preußischer Kulturbesitz, Bayerische Staatsbibliothek München, and Herzog August Bibliothek Wolfenbüttel
The Union Catalogue of Books Printed in German Speaking Countries in the 17th Century is a retrospective national bibliography for the period 1601 to 1700. Included are all German-language items as well as any work printed and published in the German speaking countries of the time, regardless of its language.
The Union Catalogue of Books Printed in German Speaking Countries in the 17th Century website