Columbia subject headings:
Europe--History--1918-1945--Congresses.
World War, 1939-1945--Underground movements--Europe--Congresses.
Harvard subject headings:
Europe--History--1918-1945--Congresses.
World War, 1939-1945--Underground movements--Europe--Congresses.
Princeton subject headings:
Anti-Nazi movement--Europe.
World War, 1939-1945--Underground movements--Europe.