"I thought Mark Felt was probably the one, which made sense because what he told Woodward was mainly the stuff the F.B.I. would have had. What he didn't tell Woodward was really anything critical about us. It wasn't inside the White House stuff, it was inside the F.B.I. stuff."
January 1, 1970
https://en.wikiquote.org/wiki/W._Mark_Felt