George Santayana, Marianne S. Wokeck, Martin A. Coleman, James Gouinlock (2015). “The Life of Reason Or The Phases of Human Progress: Reason in Art, Volume VII, Book Four”, p.118, MIT Press
Thorstein Veblen (2016). “BUSINESS & ECONOMICS Premium Collection: 25+ Titles in One Volume: The Theory of Business Enterprise, The Higher Learning in America, The Vested Interests and the Common Man, On the Nature of Capital…: The Theory of the Leisure Class, The Beginning of Ownership, The Preconceptions of Economic Science, The Industrial System and the Captains of Industry, The Socialist Economics of Karl Marx…”, p.183, e-artnow
Tony Robbins (2007). “Awaken the Giant Within: How to Take Immediate Control of Your Mental, Emotional, Physical and Financial”, p.317, Simon and Schuster
Robert Graves (2006). “The Long Weekend : a Social History of Great Britain 1918-1939: And, The Reader Over Your Shoulder : a Handbook for Writers of English Prose”, Carcanet Press
Richard Baxter, William Orme (1830). “The practical works of the Rev. Richard Baxter: with a life of the author, and a critical examination of his writings”, p.19