Journalists Bob Woodward and Carl Bernstein, who broke the Watergate story with, perhaps, the most famous anonymous source in journalism history, said it’s especially important to protect such sources now. During a rare joint appearance, the duo told an audience at Harvard University yesterday that they were concerned about prosecutors going after reporters and their sources, citing the investigation into the leak of a covert CIA officer’s identity.‘‘It is a really bad thing, for journalism, for the country. You will dry up the real story of what is going on in government,’’ Woodward said.Several reporters were subpoenaed to testify in the investigation into the disclosure of the identity of CIA officer Valerie Plame. Plame is the wife of former US ambassador Joseph Wilson, who questioned the veracity of intelligence cited by the Bush administration in the run-up to the Iraq war.Wilson has alleged his wife was unmasked in retaliation. The probe resulted last month in the indictment of I Lewis ‘‘scooter’’ Libby, 55, vice President Dick Cheney’s former chief of staff, on charges that he lied to FBI agents and a federal grand jury about how he learned about Plame’s identity and when he subsequently told reporters.Bernstein blasted the Bush administration, saying the CIA probe exposed ‘‘the disingenuousness, the lying, the willingness of this presidency to go after those who disagree with it and discredit them.’’