Columbia subject headings:
Harvard subject headings:
Normans--Italy--Sicily--Congresses.
Sicily (Italy)--History--1016-1194--Congresses.
William II, King of Sicily, 1153 or 1154-1189--Congresses.
Princeton subject headings:
Normans--Sicily (Italy)--Congresses.
Sicily (Italy)--History--1016-1194--Congresses.
William I, King of Sicily, 1120?-1166--Congresses.
William II, King of Sicily, 1153 or 1154-1189--Congresses.