Columbia subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Sicily (Italy)--Politics and government--To 1282.
Sicily (Italy)--Social conditions.
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Political parties--Italy--Sicily--History.
Sicily (Italy)--Politics and government--To 1282
Sicily (Italy)--Social conditions
Princeton subject headings:
Sicily (Italy)--Politics and government--To 1282.