Wayne W. Dyer (2009). “Your Erroneous Zones: Step-by-Step Advice for Escaping the Trap of Negative Thinking and Taking Control of Your Life”, p.30, Harper Collins
Benjamin Disraeli, Edmund Gosse, Robert Arnot (1904). “The works of Benjamin Disraeli, earl of Beaconsfield: embracing novels, romances, plays, poems, biography, short stories and great speeches”