Tony Robbins (2007). “Awaken the Giant Within: How to Take Immediate Control of Your Mental, Emotional, Physical and Financial”, p.303, Simon and Schuster
Chogyam Trungpa (2010). “The Collected Works of Chogyam Trungpa: Volume Three: Cutting Through Spiritual Materialism; The Myth of Freedom; The Heart of the Bud dha; Selected Writings”, p.80, Shambhala Publications