I'm currently studying the similiarities and differences between the role of terror/social engineering and xenophobia , in both Idealogy and execution in the USSR (under Stalin ) and Nazi Germany for a school project ( this the IBDP history IA if anyone's familiar with it).
One part of this project involves me analyzing two key sources(secondary or primary) on my topic . One of the sources that I picked up was the "Origins of totallitarianism" by Hannah Arendt and I was wondering if there was a paper that was similiar in significance but arguing against/ taking a different line of thinking on comparing Stalinism and Nazism. I don't know how exactly do primary sources factor into a debate like this but if there are any famous ones that are often sites in these discussions I'd like to know about them as well!
While there's room for further discussion, especially concerning your main point of interest, this previous answer by /u/commiespaceinvader deals with certain controversial aspects of Arendt's work.