Sales through bookstores rose for the third straight month in April. According to preliminary estimates from the U.S. Census Bureau, bookstore sales in April increased 4.8%, to $845 million; sales for the entire retail segment were up 7% in the month. For the January-through-April period, bookstore sales managed to eke out a 0.5% gain over the same period in 1997, to $4.07 billion.