Columbia subject headings:
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--Sources.
Harvard subject headings:
World War, 1914-1918--Diplomatic history
World War, 1914-1918--Documents, etc., sources.
World War, 1914-1918--Sources
Princeton subject headings:
World War, 1914-1918--Diplomatic history.
World War, 1914-1918--Documents, etc., sources.