Robert M. Sapolsky (2004). “Why Zebras Don't Get Ulcers: The Acclaimed Guide to Stress, Stress-Related Diseases, and Coping - Now Revised and Updated”, p.286, Macmillan
Bruce H. Lipton (2015). “The Biology of Belief 10th Anniversary Edition: Unleashing the Power of Consciousness, Matter & Miracles”, p.186, Hay House, Inc