In the best-selling book Think And Grow Rich, author Napoleon Hill claims that:
This secret was extensively used by President Woodrow Wilson, during the World War. It was passed on to every soldier who fought in the war...
This is one of the first and best selling personal success books, and Napoleon Hill has become very famous within the genre.
I have been looking for some external verification of his claim that the contents of his work were used by president Woodrow Wilson, and so far I have managed to turn up nothing but sources directly quoting his book. Can anyone help me verify this?