1. Arthur Koestler, The Invisible Writing ( New York: Macmillan, 1954 ), p. 194.
2. Ruth Fischer, Stalin and German Communism ( Cambridge, MA: Harvard University Press, 1948 ), p. 611;
3. Richard G. Powers, Not Without Honor: The History of American Anti-Communism ( New Haven, CT: Yale University Press, 1998 ), p. 120;
4. Ronald Clark, Einstein: The Life and Times ( New York: World Publishing, 1971 ), p. 494.
5. Peter Bell, Chamberlain, Germany and Japan, 1933–4 ( London: Macmillan, 1996 ), pp. 11–12.