Columbia subject headings:
Emperors--Holy Roman Empire--Correspondence.
Frederick II, Holy Roman Emperor, 1194-1250--Correspondence.
Holy Roman Empire--History--Frederick II, 1215-1250--Sources.
Konrad IV, King of Germany, 1228-1254--Correspondence.
Records (Documents)
Sicily (Italy)--History--1194-1282--Sources.
Harvard subject headings:
Emperors--Holy Roman Empire--Correspondence.
Frederick II, Holy Roman Emperor, 1194-1250--Correspondence.
Holy Roman Empire--History--Frederick II, 1215-1250--Sources.
Konrad IV, King of Germany, 1228-1254--Correspondence.
Princeton subject headings:
Emperors--Holy Roman Empire--Correspondence.
Frederick II, Holy Roman Emperor, 1194-1250--Correspondence.
Holy Roman Empire--History--Frederick II, 1215-1250--Sources.
Konrad IV, King of Germany, 1228-1254--Correspondence.
Sicily (Italy)--History--1194-1282--Sources.