Columbia subject headings:
Harvard subject headings:
Submarines (Ships)--Germany--Markings.
World War, 1939-1945--Naval operations, German.
World War, 1939-1945--Naval operations--Submarine.
Princeton subject headings:
Submarines (Ships)--Germany--Markings.
World War, 1939-1945--Naval operations, German.
World War, 1939-1945--Naval operations--Submarine.