<Li> Jump up ^ Service (2007: 167) </Li> <Li> Jump up ^ Brown, The Rise and Fall of Communism, pp 88 - 90 </Li> <Li> Jump up ^ Anne Applebaum, Gulag: A History . 2003 . 736 pp. excerpt and text search </Li> <Li> Jump up ^ The exact number of victims is unknown by a factor of 10, from several million upwards to 20 million . Service says 1.5 million were arrested and 200,000 were eventually released . Service ch 31 esp p. 356 . The lowest estimates by Getty give more than 300,000 executions in each of the years 1937 and 1938 . J. Arch Getty and Roberta T. Manning, eds., Stalinist Terror: New Perspectives (1993) </Li>

What factor contributed to the rise of communism in the early twentieth century