Columbia subject headings:
Fortification--Italy--Terni (Province)--History--To 1500.
Towers--Italy--Terni (Province)--History--To 1500.
Harvard subject headings:
Fortification--Italy--Terni (Province)--History--To 1500.
Towers--Italy--Terni (Province)--History--To 1500.
Princeton subject headings:
Fortification--Italy--Terni (Province)--History--To 1500.
Towers--Italy--Terni (Province)--History--To 1500.