Anne Frank once taped over two pages in her diary with brown sticky paper, leaving a small puzzle as to what material the Jewish teenager, who had no idea of how famous her diary would later become, wanted to exclude.
Now Dutch researchers have revealed the answer: corny jokes and a summary of her ideas about sexual education when she was aged just 13.
"Anybody who reads the passages that have now been discovered will be unable to suppress a smile," said Frank van Vree, director of the NIOD Institute for War, Holocaust and Genocide Studies of the Netherlands.