Maugham William Somerset. A Writers Notebook.
Morgan Ted. Maugham. N.Y., 1980.
Nicolai Valter. The German Secret Service, 1924.
Quoirrin Marianne. Agentinnen aus Liebe. BRD, 1999.
Rowan and Deindorfer. Secret Service. N.Y., 1961.
Singer Kurt. Three Thousand Years of Espionade. N.Y., 1948.
Singer Kurt. Spies Who Changed History by W. Ludecka.
Singer Kurt. Spies and Traitors. London, 1953.
Singer Kurt. The Men in the Trojan Horse. Boston, 1953.
Wolf Markus. Spionajechef im geheimen Krieg. Erinnerungen. BRD, 1998.
Whiton Charles. The Greatest Spies of the World, London.