You can take 126 to Yangjiashan, then transfer to 30 1 and get off at Dingwangtai. 17 station or so.

Or take 126 or 127 to the railway station, and then transfer to San Lv Road and 202 to Dingwangtai.

Dingwangtai is a book market, next to Xinhua Bookstore in Hunan Province. I don't know if this is the Changsha Book City you mentioned. - -|||