Columbia subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Naples (Kingdom)--History--1016-1268--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.
Harvard subject headings:
Frederick II, Holy Roman Emperor, 1194-1250--Congresses.
Italy, Southern--History--Congresses.
Naples (Kingdom)--History--1016-1268--Congresses.
Sicily (Italy)--History--1016-1194--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.
Princeton subject headings:
Italy, Southern--History--Congresses.
Sicily (Italy)--History--1194-1282--Congresses.