Columbia subject headings:
Europe--History--20th century.
Harvard subject headings:
Europe--History--1918-1945.
Europe--History--20th century.
World War, 1914-1918--Causes
World War, 1939-1945--Causes.
Princeton subject headings:
Diplomacy--History--20th century.
Europe--History--20th century.
Europe--Relations--Great Britain.
Great Britain--History--20th century.
Great Britain--Relations--Europe.