Columbia subject headings:
Harvard subject headings:
France--Foreign relations--1914-1940.
Maginot Line (France)
Rohrbach-lès-Bitche (France)--History--20th century.
Princeton subject headings:
Fortification--France--Rohrbach-lès-Bitche Region--History--20th century.
Maginot Line (France)
Rohrbach-lès-Bitche Region (France)--History--20th century.