Columbia subject headings:
World War, 1939-1945--Naval operations, British.
World War, 1939-1945--Naval operations--Submarine.
Harvard subject headings:
Great Britain. Royal Navy
World War, 1939-1945--Naval operations, British.
World War, 1939-1945--Naval operations--Submarine.
Princeton subject headings:
Submarines (Ships)--Germany--History.
Submarines (Ships)--Great Britain--History.