Know How Quotes - Page 14
Mother Teresa, Mother Teresa of Calcutta (2010). “In the Heart of the World: Thoughts, Stories & Prayers”, p.11, New World Library
Howard Luck Gossage (1995). “The book of Gossage: a compilation, which includes "Is there any hope for advertising?"”
"The Moral Maxims and Reflections". Book by François de La Rochefoucauld. Maxim 423, 1678.