The book was written in German and titled "Rosi sucht Geld," which translates to "Rosi Looks For Money" or "Rosi Needs Money" in English. It was published in 2013 as part of a city-sponsored initiative to crowdsource ideas from the public on how to teach children about sex work, according to the Berlin government. The contents of the book are for children aged 6 to 12, according to the book's description.
That said, in its opening pages, "Rosi sucht Geld" raises the question, "How do I tell my child?" That question implies the text is for parents seeking help teaching children about sex work, which is legal in Germany.