Jeffrey Gitomer (2013). “Jeffrey Gitomer's 21.5 Unbreakable Laws of Selling: Proven Actions You Must Take to Make Easier, Faster, Bigger Sales....Now and Forever”, p.161, Bard Press
Arnold Bennett (2013). “How to Live on Twenty-Four Hours a Day: The Secret Edition - Open Your Heart to the Real Power and Magic of Living Faith and Let the Heaven Be in You, Go Deep Inside Yourself and Back, Feel the Crazy and Divine Love and Live for Your Dreams”, p.17, Lulu Press, Inc