Columbia subject headings:
Espionage--Germany.
Gebauer, Karl, 1931-
Spies--Germany--Biography.
World War, 1939-1945--Secret service--Germany.
Harvard subject headings:
Gebauer, Karl, 1931-
Secret service--Germany (East)
Secret service--Germany (West)
Spies--Germany (East)--Biography.
Spies--Germany (West)--Biography.
Princeton subject headings:
Gebauer, Karl, 1931-
Secret service--Germany (East)
Secret service--Germany (West).
Spies--Germany (East)--Biography.
Spies--Germany (West)--Biography.