Columbia subject headings:
Harvard subject headings:
Radio broadcasting--Poland--Warsaw--History--20th century.
Warsaw (Poland)--History.
World War, 1939-1945--Communications.
World War, 1939-1945--Poland--Warsaw.
Princeton subject headings:
Poland--History--Occupation, 1939-1945.
Polskie Radio.
Radio broadcasting--Poland--Warsaw.
Warsaw (Poland)--Siege 1939.