Wolfe, Robert (June 2006). "Gustav Hilger: From Hitler's Foreign Office to CIA Consultant." Project on Government Secrecy, Federation of American Scientists. Historians View Newly Released CIA Records.
Wolfe, Robert (June 2006). "Gustav Hilger: From Hitler's Foreign Office to CIA Consultant." Project on Government Secrecy, Federation of American Scientists. Historians View Newly Released CIA Records.