Columbia subject headings:
Viterbo (Italy)--History--To 1500.
Viterbo (Italy)--Politics and government.
Harvard subject headings:
Viterbo (Italy)--History--To 1500.
Viterbo (Italy)--Politics and government--To 1500.
Viterbo (Italy)--Politics and government.
Princeton subject headings:
Viterbo (Italy)--History--To 1500.
Viterbo (Italy)--Politics and government.