I've never heard of Guido Knopp, but I had a chance to visit Dachau a bunch of years ago. There was a first rate not overlarge museum there and I had a chance to purchase a very good book published in Germany, in more than one language I believe, Konzentrazienlager Dachau, which went into some detail on events and publications leading up to the founding of the Camp in '33. There was also a rather sad little sign at the train station alerting tourists that there was more to see in Dachau.

I also remember studying in a law library in Stanford amongst shelves and shelves of foreign law books. I remember a bunch of English case law books from their colonies in Africa, full of the dry narrative of person to person anguish only with African names instead of European, and a group of Austrian law books post Anschluss, full of laws involving what jobs Jews could have and who they could and (mostly) could not marry. I wish my memory was more detailed, but I recall being impressed by the amount of ink spent on the matter.