Veteran journalist Bob Woodward said Sunday that one day it will be possible to discern the identities of his sources for his new book about the Trump administration based on his notes and documentation.

"Yes. And most specifically, I tape recorded these interviews with nearly everyone," Woodward said during an interview with CNN when asked about his reporting methodology.

To compile Fear: Trump in the White House, Woodward relied heavily on unnamed sources, who gave him details he then sought to independently confirm. Woodward and Carl Bernstein employed a similar method when the pair covered the Watergate scandal in the 1970s for the Washington Post, but his approach has been criticized by the Trump White House seeking to undermine some of the more damaging anecdotes included for publication.

"I have thousands of pages of documents, hundreds of hours with people who were participants, and the agreement with the sources was, I'm not going to name you, but I'm going to use this information if I can verify it," Woodward said Sunday.

"Somebody is going to be able to go back and do an archaeological dig as they've done on Watergate," he continued. "Carl Bernstein's and my papers are at the University of Texas, all the notes, all the data, all the story drafts, and people have gone and looked at that."

Fear was released last week. More than 750,000 copies were sold in its first official day on bookshelves and online around the U.S.

Woodward's documentation for Fear is expected be displayed at his alma mater, Yale University.