Stephen R. Covey (2015). “The Stephen R. Covey Interactive Reader - 4 Books in 1: The 7 Habits of Highly Effective People, First Things First, and the Best of the Most Renowned Leadership Teacher of our Time”, p.377, Mango Media Inc.
Edmund Burke, T. O. McLoughlin, Paul Langford, James T. Boulton (1997). “The Writings and Speeches of Edmund Burke: Volume I: The Early Writings”, p.168, Oxford University Press on Demand
Saint Augustine (Bishop of Hippo.), Saint John Chrysostom, Philip Schaff (1905). “A Select Library of the Nicene and Post-Nicene Fathers of the Christian Church: St. Chrysostom: Homilies on Galatians, Ephesians, Philippians, Colossians, Thessalonians, Timothy, Titus, and Philemon”