well there is the diary of Ann Frank. But there is another book called the Cage
I personally read The Cage, By Ruth Minsky Sender. It tells of her journey through the holocaust, before the Holocaust, Ruth lived with her 3 brothers and 3 sisters, and her mother (her father died before the Holocaust). She lived in Lodz, Poland. this became a Ghetto. She lived there until moved to many different concentration camps including Auschwitz. Once her mother is taken she is in charge of her 3 brothers. (her three sisters were in Russia at the time.) Ruth is Put through twists and turns by the Nazis, a heart wrenching experience. I have personally met her and she told me her story, it was even more powerful to hear it from her than when I read it. She still lives today, well into her 90's.
I highly recommend this book