Columbia subject headings:
Harvard subject headings:
Aristocracy (Social class)--Italy--Viterbo.
City planning--Italy--Viterbo.
Viterbo (Italy)--Genealogy.
Viterbo (Italy)--History--Sources.
Viterbo (Italy)--History--To 1500.
Viterbo (Italy)--History.
Princeton subject headings:
Aristocracy (Social class)--Italy--Viterbo--History.
City planning--Italy--Viterbo--History.
Viterbo (Italy)--History.