Columbia subject headings:
Harvard subject headings:
Germany--History, Naval--20th century.
Germany. Kriegsmarine--Biography.
Germany. Kriegsmarine--History--World War, 1939-1945.
Sorge, Siegfried, 1898-1989.
Sorge, Siegfried.
Princeton subject headings:
Germany--History, Naval--20th century.
Germany. Kriegsmarine--Biography.
Germany. Kriegsmarine--History--World War, 1939-1945.
Sorge, Siegfried, 1898-1989.