Bungaku Shoujo, or Book Girl in the English releases, is a collection of Light Novel works by Mizuki Nomura. There are about 16 novels in the series with eight being part of the main story four being short story collections, and four being side stories. There are 5 animated adaptations: 4 of them being OVAs and the recent movie -- just note that they all adapt the last half the series, so if you're going to read the books, read them first. In addition, several of the novels have been adapted to manga.