Columbia subject headings:
Civilization, Medieval--13th century.
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--Frederick II, 1215-1250.
Holy Roman Empire--Kings and rulers--Biography.
Naples (Kingdom)--History--1016-1268.
Naples (Kingdom)--Kings and rulers--Biography.
Sicily (Italy)--History--1194-1282.
Sicily (Italy)--Kings and rulers--Biography.
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--Frederick II, 1215-1250.
Holy Roman Empire--Kings and rulers--Biography.
Naples (Kingdom)--History--1016-1268.
Naples (Kingdom)--Kings and rulers--Biography.
Sicily (Italy)--History--1194-1282
Sicily (Italy)--Kings and rulers--Biography.
Princeton subject headings:
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--Frederick II, 1215-1250.
Holy Roman Empire--Kings and rulers--Biography.