After three consecutive months of gains, bookstore sales slipped 0.9% in September, to $1.49 billion, according to preliminary estimates from the U.S. Census Bureau. Sales for the entire retail segment rose 8.8% in the month. The bureau did slightly revise its bookstore estimate for August, dropping the sales figure of $2.10 billion to $2.08 billion. Still, bookstore sales were up a hefty 14.1% in August. For the first nine months of 2003, bookstore sales rose 2.6%, to $12 billion, while sales for all of retail increased 5.3%.