At the Communist International's 7th Congress, held in July–August 1935, the Soviet government encouraged Marxist–Leninists to unite with other leftists as part of a popular front against fascism.[3]
Haslam, Jonathan (1979). "The Comintern and the Origins of the Popular Front 1934–1935". The Historical Journal. 22 (3): 673–691. doi:10.1017/s0018246x00017039. S2CID159573290.
Khlevniuk, Oleg V. (2015). Stalin: New Biography of a Dictator. Translated by Nora Seligman Favorov. Yale University Press. ISBN978-0-3001-6388-9.