White Terror: Cossack Warlords in the Trans-Siberian by Jamie Bisher is highly recommended. It is a comprehensive, detailed book that tells the story of the Russian Civil War in Siberia. When I read it, I made notes that I will someday turn into wargame scenarios.
It is compelling and horrific at the same time. By the time I finished it, I was emotionally exhausted. The cruelty of this conflict is well known, the intensity of that cruelty in the Russian Far East was astounding.
If you are interested in the Russian Civil War, Cossacks, or history in general, this book is for you. There are now soft cover and ebook versions, making it accessible to all.