Columbia subject headings:
Harvard subject headings:
Letters--Bibliography--Catalogs.
Lower Saxony (Germany)--History--Sources--Bibliography--Catalogs.
Niedersächsisches Staatsarchiv in Wolfenbüttel--Catalogs.
Princeton subject headings:
Letters--Catalogs.
Lower Saxony (Germany)--History--Sources--Bibliography--Catalogs.
Niedersächsisches Staatsarchiv in Wolfenbüttel--Catalogs.