Will Rogers, Bryan B. Sterling, Frances N. Sterling (1993). “Will Rogers' World: America's Foremost Political Humorist Comments on the Twenties and Thirties--and Eighties and Nineties”, p.107, Rowman & Littlefield
Wayne W. Dyer (2011). “Pulling Your Own Strings: Dynamic Techniques for Dealing with Other People and Living Your Life As You Choose”, p.9, Harper Collins