Columbia subject headings:
Harvard subject headings:
Europe--History, Military--20th century.
Europe--History--20th century.
World War, 1914-1918
World War, 1914-1918--Europe.
World War, 1939-1945--Europe.
World War, 1939-1945.
Princeton subject headings:
Europe--History, Military--20th century.
Europe--History--20th century.
World War, 1914-1918--Europe.
World War, 1939-1945--Europe.