Columbia subject headings:
Military intelligence--Germany--History--20th century--Sources.
World War, 1939-1945--Secret service--Germany--Sources.
Harvard subject headings:
Military intelligence--Germany--History--20th century--Sources.
World War, 1939-1945--Secret service--Germany--Sources.
World War, 1939-1945--Secret service--Sources.
Princeton subject headings:
Military intelligence--Germany--History--20th century--Sources.
World War, 1939-1945--Secret service--Germany--Sources.