I have spent the past few years of my life studying the ideology of Marxism-Leninism, which was the official ideology of the Soviet Union. Marxism-Leninism dominated the last century, during which a full third of the planet’s surface was Marxist-Leninist.
Over the break, I finally finished, after a year of study, the massive Grundlagen des Marxismus-Leninism: Lehrbuch. This was an official, 850-page Soviet-approved German translation from the Russian. It was used as a textbook for the purpose of instructing the citizens of the Deutsche Demokratische Republik (the DDR, or East Germany) on how to be good Communists.