Columbia subject headings:
Fortification--France.
France--History--German occupation, 1940-1945.
Military architecture.
Harvard subject headings:
Fortification--France
France--History--German occupation, 1940-1945.
Military architecture.
Princeton subject headings:
Bunkers (Fortification)--Europe--Exhibitions.
Coast defenses--France--Exhibitions.
France--History--German occupation, 1940-1945--Exhibitions.