This listing is for 6 Book of the Month editions that were published from 2003-2004. They are in excellent to like new condition. They appear to have been lightly or not used at all. There is no writing in these books. The Bobbsey Twins Mystery series was launched in 1904 by Grosset & Dunlap. The series was ghost written under the name Laura Lee Hope by a group of writers known as the Stratemeyer Syndicate. The books follow the adventures of two sets of twins: 12-year-olds Nan and Bert and 6-year-olds Flossie and Freddie. The first of 72 books was published in 1904, the last in 1979, with a separate series of 30 books published from 1987 through 1992.