If you want something a little less dry and history book-like and a little more personal try reading Anna-Louise Strong's This Soviet World. Written in 1936 she actually had a first hand view into what was happening in the Soviet Union at the time.
You can find more of her works on her time in the Soviet Union and later in China (her work on Tibet especially is an excellent resource) here: https://www.marxists.org/reference/archive/strong-anna-louise/