2 sobering books you may wish to read both by Lord Liverpool "The Scourge Of The Swastika" also "The Scourge Of Bushido" the second book will really affect you I have read both (Have copies) and can categorically state the Bushido one had me aghast it was about as inhumane as you can get it is so awful you cannot get angry just sad, it makes the Dr. Mengle experiments look positively benign.
One more book is Defy the Darkness a tale of courage in the shadow of Mengle By Rosenblum & Kohn a modern book but pretty damn awful, inspirational for its courage portrayed.
Buchenwald camp held a true horror of a woman called Ilse Koch (Commandants wife from memory) who loved tattoos she would roam the compounds looking for well tattooed victims pick them out they were then taken away killed by lethal injection, skinned and the tanned product made into lamp shades for her. She also had the fat rendered down and made into soap so she could be clean always accompanied by her two Rottweilers she laughed gaily as they tore prisoners to pieces on various occasions, thankfully justice prevailed and she had her neck stretched after her trial post WWII.
I was close BAR pity she did not get the gallows