Columbia subject headings:
Harvard subject headings:
Holy Roman Empire--History--Frederick I, 1152-1190.
Italy--History--476-1268.
Lombard League.
Lombardy (Italy)--History--To 1535.
Princeton subject headings:
Holy Roman Empire--History--Frederick I, 1152-1190.
Italy--History--476-1268.
Lombard League.
Lombardy (Italy)--History--To 1535.