THE ROTE KAPELLE. The CIA's History of Soviet Intelligence and Espionage Networks in Western Europe, 1936-1945. In: Paul L. Kesaris (Hrsg.): CLASSIFIED STUDIES IN TWENTIETH-CENTURY DIPLOMATIC AND MILITARY HISTORY. University Publications of America, Inc., Washington, D.C. 1979, ISBN 0-89093-203-4, S.199 (Online).
cia.gov
Mark A. Tittenhofer: The Rote Drei: Getting Behind the 'Lucy' Myth, CIA Historical Review Program Release in full 22 Sept 93, S. 28; PDF
