Derek H Aldcroft et Steven Morewood, The European Economy Since 1914, London and New York, 5th, (ISBN978-0-415-43889-6, lire en ligne), p. 399
Patrick R. Osborn, Operation Pike: Britain Versus the Soviet Union, 1939–1941, Westport, Connecticut, London, Greenwood Press, (ISBN0-313-31368-7, lire en ligne), p. 76