Perhaps one of the most popular women of the 20th century, Jacqueline Kennedy Onassis may also be one of the most written about. The latest, Just Jackie: Her Private Years by Ed Klein, published by Ballantine, hits the charts with 140,000 copies in print after three trips to press. Journalist Klein (he most recently penned All Too Human: The Love Story of Jack and Jackie) is in the midst of a 13-city tour that ends in Pittsburgh, Pa., on November 11. Kickoff was a cover-story book excerpt in People.