Columbia subject headings:
Air defenses--Italy--Palermo (Province)--History--20th century.
Bunkers (Fortification)--Italy--Palermo (Province)--Catalogs.
Military architecture--Italy--Palermo (Province)--History--20th century.
Palermo (Italy : Province)--Buildings, structures, etc.
Palermo (Italy : Province)--History, Military--20th century.
Harvard subject headings:
Air defenses--Italy--Palermo (Province)--History--20th century.
Bunkers (Fortification)--Italy--Palermo (Province)--Catalogs.
Military architecture--Italy--Palermo (Province)--History--20th century.
Palermo (Italy : Province)--Buildings, structures, etc.
Palermo (Italy : Province)--History, Military--20th century.
Princeton subject headings: