Columbia subject headings:
Harvard subject headings:
Germany--History--Interregnum, 1254-1273--Congresses.
Holy Roman Empire--History--Interregnum, 1254-1273--Congresses.
Richard, King of the Romans, 1209-1272--Congresses.
Princeton subject headings:
Germany--History--Interregnum, 1254-1273--Congresses.
Holy Roman Empire--History--Interregnum, 1254-1273--Congresses.
Richard, King of the Romans, 1209-1272--Congresses.