Leo Tolstoy (2016). “WHAT IS ART? & WHEREIN IS TRUTH IN ART? (Meditations on Aesthetics & Literature): On the Significance of Science and Art, Shakespeare and the Drama, The Works of Guy De Maupassant, A. Stockham'sTokology, Amiel's Diary, S. T. Seménov's Peasant Stories, Stop and Think!...”, p.46, e-artnow
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.560, Mango Media Inc.
Thomas Troward (2013). “The Edinburgh Lectures on Mental Science: Spirit and Matter, Subjective and Objective Mind, Power of Subconscious Mind (New Thought Edition - Secret Library)”, p.22, Lulu Press, Inc