Columbia subject headings:
Germany--Church history--843-1517--Congresses.
Holy Roman Empire--Church history--Congresses.
Harvard subject headings:
Catholic Church--Germany--Rhineland--History--Congresses.
Rhineland (Germany)--Church history--Congresses.
Princeton subject headings:
Germany--Church history--843-1517--Congresses.
Holy Roman Empire--Church history--Congresses.