SAN FRANCISCO -- Lawyers for two San Francisco Chronicle reporters argued Friday that the First Amendment protects them from revealing their source for the secret testimony of Barry Bonds and other elite athletes ensnared in the government's steroids probe. Lance Williams and Mark Fainaru-Wada are fighting a subpoena compelling them to testify before a grand jury investigating the leak. The two reporters published a series of stories and a book based largely on transcripts of testimony by Bonds, Jason Giambi and others who testified in the investigation of the Bay Area Laboratory Co-Operative. .