Columbia subject headings:
Harvard subject headings:
Archives--Germany--Aurich--Catalogs.
Niedersächsisches Staatsarchiv in Aurich--Catalogs.
Ostfriesland (Germany)--History--Sources--Bibliography--Catalogs.
Princeton subject headings:
Ostfriesland (Germany)--Politics and government--Sources.
Prussia (Germany)--Politics and government--1740-1815.