Columbia subject headings:
Harvard subject headings:
Flanders (France)--History, Military--20th century--Pictorial works.
Fortification--France--Flanders--History--20th century--Pictorial works.
Military architecture--France--Flanders--History--20th century--Pictorial works.
Military engineering--France--Flanders--History--20th century--Pictorial works.
World War, 1914-1918--France--Flanders--Pictorial works.
Princeton subject headings:
Flanders (France)--History, Military--20th century--Pictorial works.
Fortification--France--Flanders--History--20th century--Pictorial works.
Military architecture--France--Flanders--History--20th century--Pictorial works.
Military engineering--France--Flanders--History--20th century--Pictorial works.
World War, 1914-1918--France--Flanders--Pictorial works.