Stephen R. Covey (1994). “Daily Reflections for Highly Effective People: Living THE SEVEN HABITS OF HIGHLY SUCCESSFUL PEOPLE Every Day”, p.140, Simon and Schuster
"The Vision: Reflections on the Way of the Soul". Book by Kahlil Gibran, translated by Juan R. I. Cole. Chapter "Children of Gods, Scions of Apes", 1994.