Yuri Bezmenov, also known as Thomas Schuman, was a subversion expert who defected to the West during the Cold War. Having worked his entire life in the KGB as a subversion agent, he participated in laying the foundations for eventual Marxist revolutions in surrounding nations.
Among his video series we find Psychological Warfare, Subversion, & Control of Western Society, a recorded lecture where he outlines and explains the KGB subversion process to an American audience.
Introduction to Subversion
The Theory of Subversion
The Four Stages of Subversion
The KGB subversion methodology works in four stages: