Wallace D. Wattles (2015). “The Science of Wallace D. Wattles: The Science of Being Well, The Science of Getting Rich & The Science of Being Great – Complete Trilogy: From one of the New Thought pioneers, author of How to Promote Yourself, New Science of Living and Healing, Hellfire Harrison, A New Christ, How to Get What You Want and Jesus The Man and His Work”, p.36, e-artnow
Dr. Robert C. Worstell, James Breckenridge Jones, Napoleon Hill (2015). “Think and Grow Rich, Updated and Complete - With If You Can Count to Four...”, p.95, Lulu.com