Well.... I suppose you could start with Mein Kampf....where Hitler goes into great detail about his disgust and loathing of the Jewish people his belief that that are rats and parasites feeding off the host of the German people. Anti-Semetism is DEEPLY ENGRAINED in European history.
Yeah, but one nutter with a screwed up monograph doesn’t make the trains run on time to Treblinka. Like I said, I’ve read the major works, and the closest I’ve come to seeing a candid discussion of contributing factors is Marci Shore’s recent *The Taste of Ashes*. There is more to this story than some thrice-gassed Austrian corporal with a poorly written rant the size of a Manhattan phone book suddenly waking to find everyone had hit the “like” button and deciding to whack over ten million of their fellow Europeans. There’s a lot of good research and publishing coming out of the region. Shore’s book and Snyder’s *Bloodlands* indicate there is a measure of revisionism or at least reevaluation occurring in the field.
Even the conventional history recognizes that the Nazis initially had no intention of killing all the Jews. What they had in mind was grand scale ethnic cleansing. With the Jews and other undesirables expelled from Europe, not murdered en masse. Though nobody was going to be bothered if a few, or a few hundred thousand, got killed in the process.
It wasn’t until January, 1942, at the earliest, if I remember correctly, that the decision was made to launch mass killing. And the major reason was that it had become obvious that due to the war there was just no way to exile the Jews in any reasonable timespan. Also the extensive German conquests in eastern Europe had multiplied by many times the number of Jews they would have to exile.
So they’d just kill them, instead.