George Bernard Shaw (2015). “George Bernard Shaw: The Collected Plays (Illustrated): 60 plays including Caesar and Cleopatra, Pygmalion, Saint Joan, The Apple Cart, Cymbeline, Androcles And The Lion, The Man Of Destiny, The Inca Of Perusalem and Macbeth Skit”, p.3702, e-artnow
Molotov's report on (29 March 1940), after the Polish defeat, as quoted in the weekly Soviet newspaper "Moscow News", published by Mezhdunarodnaya Kniga, April 1, 1940.