H. Jackson Brown Jr. (2007). “Complete Life's Little Instruction Book: 1,560 Suggestions, Observations, and Reminders on How to Live a Happy and Rewarding Life”, p.185, Thomas Nelson Inc
Joel Garreau (2005). “Radical Evolution: The Promise and Peril of Enhancing Our Minds, Our Bodies -- and What It Means to Be Human”, p.112, 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.114, Broadway Books