The book "Be prepared for danger in times of peace-reflections on the 20 years of the demise of the CPSU" is very good. I personally watched it three times. I suggest you have a look. Chen Zhihua and Ma Longshan compiled the Outline of the Rise and Fall History of the Soviet Union; The history of the rise and fall of the Soviet Union was compiled by Zhou; The reasons and lessons of the evolution of the Soviet Union; October Revolution and Socialism; Written by Marshal Stalin and Russian Boris karpov, these books are serious academic works, and I have studied them all. This is good for your research. I hope it works for you.