Columbia subject headings:
Church and state--Europe--History.
Church and state--Holy Roman Empire--History.
Popes--Temporal power--History.
Harvard subject headings:
Church and state--Catholic Church
Papacy--History--Middle Ages, 600-1500.
Papacy--Temporal power.
Princeton subject headings:
Church and state--Catholic Church--History.
Europe--Kings and rulers--Religious aspects--History.
Papacy--History--To 1309.
Popes--Temporal power.