Columbia subject headings:
Castles--Italy--Valle d'Aosta.
Fortification--Italy--Valle d'Aosta.
Harvard subject headings:
Castles--Italy--Valle d'Aosta.
Fortification--Italy--Valle d'Aosta.
Princeton subject headings:
Castles--Italy--Valle d'Aosta.
Fortification--Italy--Valle d'Aosta.