Columbia subject headings:
Harvard subject headings:
Anti-submarine warfare--History.
Submarines (Ships)--Germany
World War, 1939-1945--Aerial operations, American.
World War, 1939-1945--Aerial operations, British.
World War, 1939-1945--Aerial operations, Canadian.
World War, 1939-1945--Naval operations, German.
World War, 1939-1945--Naval operations--Submarine.
Princeton subject headings:
World War, 1939-1945--Naval operations--Submarine.