HUMAN EVENTS ONLINE :: Fact, Fiction, and The Da Vinci Code by Darrell L. Bock:
"Underscoring this impression to be more than a novel, the author claims his work is thoroughly researched and has characters of high credibility pour forth the novel's ideas. In fact, Dan Brown has said on his web site that he wanted these issues discussed because the theories he sets forth have been espoused for some time.
Many writers have obliged him on the matter of discussion and have challenged his claims. These include my Breaking the Da Vinci Code as well as books by Amy Wellborn (De-Coding Da Vinci), Richard Abanes (The Truth Behind the Da Vinci Code), James Garlow with Peter Jones (Cracking Da Vinci's Code), and Carl Olson with Sandra Miesel (The Da Vinci Hoax). "