Betty Shapian, a public relations professional who spent 35 years promoting bestselling authors, died of cancer on April 15 in Los Angeles. She was 73. Shapian's publishing career began at Doubleday, in its foreign department and, later, in publicity. She spent eight years as assistant to Doubleday president Nelson Doubleday. In 1967, she was asked to open a West Coast branch of Doubleday to handle its touring writers, and subsequently represented Alex Haley, James Michener, Yitzhak Rabin and Erma Bombeck, among many others. In the mid-'70s, Shapian launched her own firm, Shapian & Associates, where she handled book publicity for a client list that included Gloria Steinem, Judith Krantz, Leon Uris, Irving Wallace, Herman Wouk, Ray Bradbury, Isaac Asimov and Pauline Kael. In 1986, after joining forces with Los Angeles-based On the Scene Productions, Shapian handled the electronic book publicity for presidents Jimmy Carter and Ronald Reagan, as well as for other authors and celebrities.