Columbia subject headings:
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Sicily (Italy)--History--1194-1282
Princeton subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--Frederick II, 1215-1250.
Italy--History--Germanic rule, 962-1268.
Sicily (Italy)--Politics and government--To 1282.