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.469, Mango Media Inc.
George Bernard Shaw (2015). “George Bernard Shaw: Collected Articles, Lectures, Essays and Letters: Thoughts and Studies from the Renowned Dramaturge and Author of Mrs. Warren’s Profession, Pygmalion, Arms and The Man, Saint Joan, Caesar and Cleopatra, Androcles And The Lion”, p.311, e-artnow