Original sentence: He focused on the Soviet Union, and the relationship between the October Revolution, Lenin's state, and the actions of Stalin.He would collaborate with Carl Friedrich to develop the concept of "totalitarianism" and apply it to the Soviets, in 1956.His Master's thesis focused on the various nationalities within the Soviet Union
Edited sentence: He focused on the Soviet Union, and the relationship between the October Revolution, Lenin's state, and the crimes of Stalin.He would collaborate with Carl Friedrich to write a book on totalitarianism, especially as it applied to the Soviets, in 1956.His Master's thesis focused on the various nationalities within the Soviet Union's empire