Glenn R. Schiraldi (2007). “10 Simple Solutions for Building Self-Esteem: How to End Self-Doubt, Gain Confidence, & Create a Positive Self-Image”, p.9, New Harbinger Publications
Patch Adams (1998). “Gesundheit!: Bringing Good Health to You, the Medical System, and Society through Physician Service, Complementary Therapies, Humor, and Joy”, p.56, Simon and Schuster