b_b recommended Richard Pipes many years ago; I read Communism: A History shortly thereafter and I wholeheartedly second his recommendation. Full disclosure: Pipes is a Reagan hawk of the 1st order but he also knows his shit. Mile-high view: Marxism-Leninism as practiced in the USSR was more accurately described as a kleptocracy than "communism" and the czarist system of patronage was replaced with the Stalinist system of Nomenklatura. China, meanwhile, went from an imperial economy to a command economy where a sizable black market/gray market accomplished many of the economic essentials that communism could not. True Marxist "communism" has never been practiced at any scale because the system as envisioned by Moore/Marx has far too many loopholes through which to drive a truckload of corruption. On a more psychological level, behavioral economics seems to indicate that for organizations larger than Dunbar's number, collectivism runs contrary to human psychological risk/reward pathways. I recommend Ariely's Predictably Irrational.