Columbia subject headings:
Piacenza (Italy)--Church history--To 1500.
Piacenza (Italy)--History--To 1500.
Harvard subject headings:
Piacenza (Italy)--Church history--To 1500.
Piacenza (Italy)--History--To 1500.
Princeton subject headings:
Piacenza (Italy)--History--Early works to 1800.