What American self-help author sold over 100 million copies of his book Think and grow Rich worldwide by 2015 after his death in 1970?
Think and Grow Rich:  First published during the Great Depression, at the time of Hill's death in 1970, "Think and Grow Rich" had sold more than 20 million copies, and by 2015 over 100 million copies had been sold worldwide. Napoleon Hill: Oliver Napoleon Hill (born October 26, 1883 – November 8, 1970) was an American self-help author.
Napoleon Hill