Gary Hamel (2012). “What Matters Now: How to Win in a World of Relentless Change, Ferocious Competition, and Unstoppable Innovation”, p.53, John Wiley & Sons
Jeremy Taylor, John Wheeldon, George Herbert (1768). “Sacred Prolusions: Or, Select Pieces from Bishop Taylor and Mr. Herbert. By the Rev. John Wheeldon, ... With a Preface and a Discourse on Rev.xviii. 21. By the Editor”, p.107
Thomas Jefferson, H. A. Washington (2011). “The Writings of Thomas Jefferson: Being His Autobiography, Correspondence, Reports, Messages, Addresses, and Other Writings, Official and Private”, p.357, Cambridge University Press
Walter Lippmann, Clinton Rossiter, James Lare (1982). “The Essential Lippmann: A Political Philosophy for Liberal Democracy”, p.157, Harvard University Press