Preliminary estimates from the U.S. Census Bureau showed retail bookstore sales increasing 2.4% last year, to $11.82 billion. The increase in bookstore sales was slightly below the 3.3% gain posted by the entire retail segment. Bookstore sales were helped by two relatively strong months at the end of 1997. Sales in November rose 4.8%, to $912 million, while preliminary estimates put December sales at $1.63 billion, a 6.5% gain over December 1996.