Spiro, E. (1971). Gehlen: Spy of the century. Random House.
Lua i Stíl Chicago (17ú heag.)Spiro, Edward. Gehlen: Spy of the Century. New York: Random House, 1971.
Lua MLA (9ú heag.)Spiro, Edward. Gehlen: Spy of the Century. Random House, 1971.
Rabhadh: Seans nach mbeach na luanna seo go hiomlán cruinn i ngach uile chás.