While sales have slipped for Mr. Clancy and Mr. King, the authors are not in danger of going the way of Irving Wallace and Arthur Hailey just yet. Sales of their earlier books in paperback have remained remarkably consistent, even as their latest hardcover sales dip. Mr. King's "Carrie," for example, his first novel, originally published in 1974, sold about 23,000 copies in both 2001 and 2002, according to Nielsen Bookscan.