The annual Mark Twain Library book fair in Redding starts today.  The 57th annual event is being held at the Redding Community Center on Lonetown Road.  More than 75,000 books in 75 different categories are up for sale.  Admission is free.  Today's hours run through 6pm.  The benefit for the Library in Redding is open tomorrow and Sunday from 10am to 4pm.  Sunday is half price day.  Monday's hours are from 9am to 4pm and people can fill a box for $10 or pay half price for individual books.