Columbia subject headings:
Europe--Civilization--20th century--Congresses.
World War, 1914-1918--Social aspects--Europe--Congresses.
Harvard subject headings:
Europe--Civilization--20th century--Congresses.
World War, 1914-1918--Social aspects--Europe--Congresses.
Princeton subject headings:
Europe--Civilization--20th century--Congresses.
World War, 1914-1918--Social aspects--Europe--Congresses.