Columbia subject headings:
Geology--Belgium--Guidebooks.
Geology--France, Northern--Guidebooks.
World War, 1914-1918--Battlefields--Belgium--Guidebooks.
World War, 1914-1918--Battlefields--France, Northern--Guidebooks.
World War, 1914-1918--Campaigns--Western Front--Guidebooks.
Harvard subject headings:
Princeton subject headings:
Geology--Belgium--Guidebooks.
Geology--France, Northern--Guidebooks.
Guidebooks.
World War, 1914-1918--Battlefields--Belgium--Guidebooks.
World War, 1914-1918--Battlefields--France, Northern--Guidebooks.
World War, 1914-1918--Campaigns--Western Front--Guidebooks.