Neither do I. They are all roundabout estimates. Kurganov's seems the only reliable approach, but it cannot distinguish direct murder from artificial famine or unnecessary wars, or casualties contrary to any military sense even in a defensive war.
A good summary of these casualties due to communism can be found in three Senate-commissioned studies: Senate Internal Security Subcommittee (SISS), Sen. Judiciary Committee:
“The Human Cost of Communism in the Soviet Union”, apprx. 1970, Robert Conquest, author of “The Great Terror
“The Human Cost of Communism in China”, Prof. Richard Walker (Un. of S.Carolina), 1971
“The Human Cost of Communism in Vietnam”, 1972, Max Friedman and David Martin (SISS)
Challenging testimony hearing, “Testimony of D. Gareth Porter”, 1972 and subsequent rebuttal hearing
“The Human Cost of Communism in Vietnam: Testimony of Daniel Teodoru”, late 1972/early 1973
In the 1990’s, French scholars produced an updating book “The Black Box of Communism” which is the master study of all of the above.
Some of these hearings are online.