<Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2015) (Learn how and when to remove this template message) </Td> </Tr> </Table> <Tr> <Td> </Td> <Td> This article needs additional citations for verification . Please help improve this article by adding citations to reliable sources . Unsourced material may be challenged and removed . (September 2015) (Learn how and when to remove this template message) </Td> </Tr> <P> The original Little House books were a series of eight autobiographical children's novels written by Laura Ingalls Wilder and published by Harper & Brothers from 1932 to 1943 . The eighth book, These Happy Golden Years, featured Laura Ingalls at ages 15 to 18 and was originally published with one page at the end containing the note, "The end of the Little House books ." The ninth and last novel written by Wilder, The First Four Years was published posthumously and unfinished in 1971 . Although her intentions are unknown, it is commonly considered part of the Little House series and is included in the 9 - volume paperback box set Little House, Big Adventure (Harper Trophy, May 1994). </P> <P> Several book series and some single novels by other writers have been published for children, young adults and adult readers . They provide fictionalized accounts of the lives of Wilder's great - grandmother Martha Morse Tucker, grandmother Charlotte Tucker Quiner, mother Caroline Ingalls, and daughter Rose Wilder Lane's childhood and teenage years, as well as Wilder's own missing years--those portions of her life not featured in her novels, including most of her adult life . One story not written by Wilder is Old Town in the Green Groves by Cynthia Rylant . It tells the story of the "lost little house" years . </P>

How many books in the little house on the prairie series