Google Inc.'s chief executive told newspaper publishers Tuesday that they should continue to rely on advertising but seek new ways to reach readers. Without providing specific recipes, Eric Schmidt laid out a few possibilities, including a site for medicine similar to the online encyclopedia Wikipedia, which lets users collectively contribute and edit entries. He urged publishers to focus on mobile technology and the development of new platforms for delivering news. Schmidt said there's still room for subscription and pay-by-the-piece journalism but he emphasized advertising, the source of 98 percent of Google's revenue, thanks to its success matching ads with a user's search terms and other keywords. "The important thing here is that advertising that is useful is going to work," he said.