Columbia subject headings:
Harvard subject headings:
Poland--History--Occupation, 1939-1945
Warsaw (Poland)--History--Siege, 1939.
World War, 1939-1945--Campaigns--Poland.
Princeton subject headings:
Poland--History--Occupation, 1939-1945.
Warsaw (Poland)--Siege 1939.
World War, 1939-1945--Campaigns--Poland.