H. Jackson Brown Jr. (2007). “Complete Life's Little Instruction Book: 1,560 Suggestions, Observations, and Reminders on How to Live a Happy and Rewarding Life”, p.74, Thomas Nelson Inc
Henry Ward Beecher (1887). “Beecher : Christian Philosopher, Pulpit Orator, Patriot and Philantropist: A Volume of Representative Selections from the Sermons, Lectures, Prayers, and Letters of Henry Ward Beecher”