Richard Carlson (1998). “Don't Sweat the Small Stuff, and It's All Small Stuff: Simple Ways to Keep the Little Things from Taking Over Your Life”, MacMillan Publishing Company
Ralph Waldo Emerson, Robert Ernest Spiller, Alfred Riggs Ferguson, Joseph Slater, Jean Ferguson Carr (1971). “The Collected Works of Ralph Waldo Emerson: Nature, addresses, and lectures”, p.27, Harvard University Press