Columbia subject headings:
Harvard subject headings:
Cities and towns, Medieval--Germany--Ruhr (Region)
Civilization, Medieval--Politics and government.
Lippe (Germany)--Church history.
Lippe (Germany)--History.
Ruhr (Germany : Region)--Church history.
Ruhr (Germany : Region)--History
Princeton subject headings:
Lippe (Germany)--History.
Ruhr (Germany : Region)--History.