Columbia subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Bibliography.
Germany--History--Frederick II, 1215-1250--Bibliography.
Germany--History--Hohenstaufen, 1138-1254--Bibliography.
Hohenstaufen, House of--Bibliography.
Holy Roman Empire--History--Frederick II, 1215-1250--Bibliography.
Holy Roman Empire--History--Hohenstaufen, 1138-1254--Bibliography.
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Bibliography.
Holy Roman Empire--History--Frederick II, 1215-1250--Bibliography.
Holy Roman Empire--History--Hohenstaufen, 1138-1254--Bibliography.
Princeton subject headings: