Columbia subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Normans--Italy--Sicily--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Normans--Italy--Sicily--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.
Princeton subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Normans--Italy--Sicily--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.