[watwut]

Nazi regime was relatively short and ended abruptly by the end of war. There is much more evidence available including witnesses.

[scrumper]

And most importantly the regime ended without having had the chance to destroy much of its document stash. The Nazis were diligent record-keepers and an absolutely enormous trove of secret files turned up after the war.

The best trawl through this marterial is the gargantuan (but highly readable) "The Rise and Fall of the Third Reich" by William Shirer, an American journalist living in Europe during Hitler's rise to power and the second world war.

[watwut]

William Shirer did not went through all that material. He was journalist and not historian.

If you are interested in result of going through all that material, read Richard Evens trilogy.

[scrumper]

I'm confused by that - the book is absolutely crammed with footnotes, references to, and direct quotes from that archive of material. Undeniably, Shirer editorializes - he doesn't write like a historian - but his book is absolutely firmly based on that material. He even says as much in his introduction.

But thank you for the other recommendation.