"Dolfje Weerwolfje" is a popular children's book series written by Dutch author Paul van Loon. The story follows a young boy named Dolfje who discovers that he transforms into a werewolf every full moon. The series explores themes of friendship, identity, and the challenges of growing up. The books are aimed at children aged 7 to 12 and are known for their engaging storytelling and humor. Dolfje is often accompanied by his best friend Timmie and faces various adventures and challenges related to his werewolf condition, making the series both entertaining and relatable for young readers.