Shakti Gawain (2015). “The Shakti Gawain Essentials: 3 Books in 1: Creative Visualization, Living in the Light & Developing Intuition”, p.279, Mango Media Inc.
Shakti Gawain (2011). “Living in the Light, 25th Anniversary Edition: Follow Your Inner Guidance to Create a New Life and a New World”, p.59, New World Library
Tom Butler-Bowdon (2010). “50 Psychology Classics: Who We Are, How We Think, What We Do: Insight and Inspiration from 50 Key Books”, p.20, Nicholas Brealey Publishing