Columbia subject headings:
Harvard subject headings:
Albert, Duke of Prussia, 1490-1568--Correspondence--Catalogs.
Ermland (Ecclesiastical principality)--History--Sources--Bibliography--Catalogs.
Ermland (Germany)--History--Sources--Bibliography--Catalogs.
Geheimes Staatsarchiv Preussischer Kulturbesitz--Catalogs.
Reformation--Germany--Prussia--Sources--Bibliography--Catalogs.
Princeton subject headings:
Albert, Duke of Prussia, 1490-1568.
Ermland (Ecclesiastical principality)--History--Sources.