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
John Locke, Ruth Weissbourd Grant, Nathan Tarcov (1996). “Some Thoughts Concerning Education: And, Of the Conduct of the Understanding”, Hackett Publishing