A book called “Fifty Shades of Grey” is stirring up quite a bit of controversy at some libraries across the country.For the Hall County Library System, though, the choice of whether to carry the book isn’t about controversy — it’s about literary merit.“We have a purchasing policy we follow,” library director Adrian Mixson said. “It has to have some kind of literary merit.”Mixson said the system does not own “Fifty Shades of Grey,” a racy romance trilogy popular with some middle-aged women.A few employees purchase books for the library based on reviews of the books, and they have not purchased this one, he said.This week, the books hold the top three spots on the New York Times best-seller list.Some libraries in Wisconsin, Georgia and Florida have either declined to order the book or pulled it from shelves. Other states soon may follow.One of those library systems that will not be stocking the books is Gwinnett County’s.“We do not collect erotica at Gwinnett County Public Library.