*Here is a typical book that discusses DOTP in relation to real politics. One could simply use it (pages 15,16). Nothing complicated. It tells it was a very practical concept. It explains how and why the Soviet CPSU officially stopped using this policy in 1961. As correctly noted in this book, the only contribution by  Stalin to the concept of DOTP was well known "Aggravation of class struggle under socialism", and so on, and so.