Primo Levi and Paul Celan are both excellent, excellent writers. Any one who wants to learn about the Holocaust should read Levi's "If This Is a Man" and "The Truce". And Paul Celan's poem "Todesfuge" is one of the most moving writings from a survivor:

https://en.wikipedia.org/wiki/Todesfuge

https://en.wikipedia.org/wiki/If_This_Is_a_Man

I don't know anything better. They will change your life.