The presence in our body politic of such a party is the only means by which democracy can be saved from its present moral chaos, from the tyranny of entrenched interests, from the insolence of a predatory officeholding party system, and from the peril of a fascist dictatorship of big business, on the one hand, or of a communist dictatorship of the proletariat, on the other [December 31, 1932]. (religion-online.org)
The USSR officially remained dictatorship of proletariat (Preamble of the Constitution of 1924 and Article 2 of the constitution of 1936) until 1977. (politics.stackexchange.com)
When you said «which aspects of communism,» I believe you wanted a comparable answer to pre-Khrushchev Soviet Union, Enver Hoxha's Albania, Mao's China, etc., i.e. socialism, i.e. dictatorship of the proletariat. (politics.stackexchange.com)