context: The first book, Pertsa and Kilu, was completed in 1948, but was not published until 1951. The growth story of the six Pertsa and Kilu books is that the boys move literally into the open waters, and the dream of becoming a sailor was replaced by boat acquisition and ownership. In the 1970s, Pertsa and Kilu were turned into a television series directed by Vili Auvinen. In 2000, Taavi Vartia made a new television series about Perts and Kili, but it was not based on Riikkilä's texts.
question: What was Väinö Riikkilä's first published book?
answers.text: Pertsa and Kilu