Executives at the companies that publish Mr. Clancy, Mr. King, Ms. Grafton and Ms. Clark acknowledge their weaker sales in 2002, but contend that the sales drops are the consequence of a weak retail economy that has hit booksellers especially hard. During the nine-week holiday season ending Jan. 4, sales at Barnes & Noble stores open at least a year were down 3 percent from the previous year. And Borders's fourth-quarter comparable-store sales at its superstores were down 2.5 percent, while sales at Waldenbooks were off 6.3 percent.