Mark Twain (2014). “Mark Twain on Common Sense: Timeless Advice and Words of Wisdom from America's Most-Revered Humorist”, p.13, Skyhorse Publishing, Inc.
"A Dictionary of Thoughts: Being a Cyclopedia of Laconic Quotations from the Best Authors of the World, Both Ancient and Modern" ed. by Tryon Edwards, F. B. Dickerson Company, (p. 52), 1908.