Please check this book out.
This political tract book outlines Marxist revolutionary tactics at subverting a democratic parliamentary government. Thus, making a 'legal' change to a social democracy which then erodes into a socialist totalitarian dictatorship. This book illustrates the 'legal' transitional communist takeover of Czechoslavakia without a shot fired. This is strikingly similar to the Hitler-led NSDAP takeover of Germany in the 1930's.