Columbia subject headings:
Catholic Church--Italy--Viterbo--History.
Papacy--History.
Viterbo (Italy)--Church history.
Viterbo (Italy)--History.
Harvard subject headings:
Catholic Church--Italy--Viterbo--History.
Papacy--History
Viterbo (Italy)--Church history.
Viterbo (Italy)--History.
Princeton subject headings:
Catholic Church--Italy--Viterbo--History.
Papacy--History.
Viterbo (Italy)--Church history.
Viterbo (Italy)--History.