Columbia subject headings:
Harvard subject headings:
Christianity and other religions--Islam--History.
Frederick II, Holy Roman Emperor, 1194-1250--Relations with Muslims.
Frederick II, Holy Roman Emperor, 1194-1250.
Holy Roman Empire--History--Frederick II, 1215-1250.
Holy Roman Empire--Kings and rulers--Biography.
Islam--Italy--History--To 1500.
Islam--Relations--Christianity--History.
Princeton subject headings:
Christianity and other religions--Islam--History.
Frederick II, Holy Roman Emperor, 1194-1250--Relations with Muslims.
Holy Roman Empire--History--Frederick II, 1215-1250.
Islam--Relations--Christianity--History.