but the first "oz" book was a big success. baum was able to give up other business ideas and make enough money to live on by writing children's books. the children who read his books often wrote to baum, and asked him to write more about "oz". this caused baum to begin a series of books set in the fantasy land of oz. in time, baum grew tired of the series. he tried to end it but his child readers kept demanding that he continue. baum met their demands through the rest of his life. he wrote 14 "oz" books in all. the last two were printed after his death in 1919.