Columbia subject headings:
Catania (Italy)--History.
Frederick II, Holy Roman Emperor, 1194-1250.
Messina (Italy)--History.
Sicily (Italy)--History--1194-1282.
Harvard subject headings:
Catania (Italy)--History.
Frederick II, Holy Roman Emperor, 1194-1250.
Messina (Italy)--History.
Sicily (Italy)--History--1194-1282
Princeton subject headings:
Catania (Italy)--History.
Frederick II, Holy Roman Emperor, 1194-1250.
Messina (Italy)--History.