Columbia subject headings:
Ruggiero I, conte di Sicilia, 1031-1101.
Sicily (Italy)--History--1016-1194.
Harvard subject headings:
Ruggiero I, conte di Sicilia, 1031-1101.
Sicily (Italy)--History--1016-1194
Princeton subject headings:
Ruggiero I, conte di Sicilia, 1031-1101.
Sicily (Italy)--History--1016-1194.