Columbia subject headings:
Harvard subject headings:
World War, 1914-1918--Germany--Rhineland--Exhibitions.
World War, 1914-1918--Germany--Ruhr (Region)--Exhibitions.
Princeton subject headings:
World War, 1914-1918--Germany--Rhineland--Exhibitions.
World War, 1914-1918--Germany--Ruhr (Region)--Exhibitions.