Candace Salima was right: The Diary of a Young Girl by Anne Frank. Here, as Paul Harvey would say, is the rest of the story, from the NY Times article:
Knopf wasn’t alone. “The Diary of a Young Girl,” by Anne Frank, would be rejected by 15 others before Doubleday published it in 1952. More than 30 million copies are currently in print, making it one of the best-selling books in history.