There are over 40 million copies printed in 70 languages all detailing the inner thoughts of the "inquisitive and in many respects precocious", Jewish 13-year-old, who was kept in hiding/captivity with her family during Nazi occupation of Amsterdam.
Anne wrote in her diary until she and her family were discovered by the Nazis in 1944 and deported to Auschwitz.
Or so it seemed until now.
Peter de Bruijn, one of the partners in the diary research and a senior researcher at the Huygens Institute for the History of the Netherlands, said the uncovered text is significant because it shows Frank's first attempt at writing in a more literary tone.
Frank Van Vree, director of the Netherlands Institute for War, Holocaust and Genocide Studies, said the jokes are of the sort that are "classics among growing children".
And about prostitution, she observed, "All men, if they are normal, go with women, women like that accost them on the street and then they go together". On prostitution, Frank noted that "in Paris they have big houses for that".
"I sometimes imagine that someone might come to me and ask me to inform him about sexual matters", Anne Frank wrote on the pages."How would I go about it?"
The hidden text was across two pages
He said: "They bring us even closer to the girl and the writer Anne Frank".
Although, bold for Frank's age, the sexual nature of the writing is not what has gripped the researchers.
The posthumously published diary of Anne Frank is world famous.
"That Anne Frank had risqué jokes in her diary speaks to her humanity", Sara Bloomfield, director of the U.S. Holocaust Memorial Museum, told NPR.
Leopold said the newly deciphered material provides an early example of how Anne "creates a fictional situation that makes it easier for her to address the sensitive topics that she writes about".
Now, through digital technology, researchers from the Anne Frank House museum and two other Dutch organizations have found that Frank hid four "dirty" jokes about sex and her perspective on sexual development, contraception, sex and prostitution. Her father Otto was the only member of the family to survive the war. During her time in hiding, she wrote two versions of the diary.
He added that the adolescent had also written about the subject in several other pages of her diary, which have already been published. Though Anne herself edited her diary with an eye to publication, the book-released eight years after her death from typhus in theBergen-Belsen concentration camp at age 15-contained additional cuts.More news: Last-gasp Jesus goal takes City to 100 points
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