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.32, Lulu.com
Edgar Allan Poe (2014). “Complete Collection of Edgar Allan Poe - 170+ eBooks (Complete Tales, Poems, Novels, Essays, Miscellaneous, Play)”, p.1201, Ageless Reads