Columbia subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--To 1517--Sources.
Sicily (Italy)--History--1194-1282--Sources.
Harvard subject headings:
Princeton subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--To 1517--Sources.
Sicily (Italy)--History--1189-1282--Sources.