Gretchen Rubin (2015). “Better Than Before: What I Learned About Making and Breaking Habits--to Sleep More, Quit Sugar, Procrastinate Less, and Generally Build a Happier Life”, p.155, Broadway Books
Joel Garreau (2005). “Radical Evolution: The Promise and Peril of Enhancing Our Minds, Our Bodies -- and What It Means to Be Human”, p.260, Broadway Books