Try "Tadeusz Borowski". Sample quotes:

"I was told about a camp where transports of new prisoners arrived each day, dozens of people at a time. But the camp only had a certain quantity of daily food rations - I cannot recall how much, maybe enough for 2, or 3 thousand - and Herr Kommandant disliked to see the prisoners starve. Each man, he felt, must receive his allotted portion. And always the camp had a few dozen men too many. So every evening a ballot, using cards or matches, was held in every block, and the following morning the losers did not go to work. At noon they were led out behind the barbed-wire fence and shot."

A (nonfiction) quote I sometimes think of in connection with World of Stone, though it's actually from The Captive Mind, is:

"Had Beta been French, perhaps he would've been an existentialist, though that wouldn't've satisfied him. He smiled contemptuously at mental speculations, for he remembered seeing philosophers fighting over garbage in the concentration camps. Human thought had no significance; subterfuge & self-deception were easy to decipher: all that really counted was the movement of matter."