1. Isabel Briggs Myers, Mary H. McCaulley, Naomi L. Quenk, and Allen L. Hammer, MBTI Manual: A Guide to the Development and Use of the Myers-Briggs Type Indicator, 3^rd ed., Consulting Psychologists Press, Palo Alto, Calif., 1998, p. 298.

2. Del Jones, “Not All Successful CEOs Are Extroverts,” USA Today, June 7, 2006, .

3. “Oprah Talks to Jerry Seinfeld,” (audio interview), O, The Oprah Magazine, November 2007, .

4. Sage Stossel, “Introverts of the World, Unite!” The Atlantic Magazine, February 14, 2006, .

5. Ibid.

6. Elaine Aron, Ph.D., , December 1, 2008.

7. Robert Ornstein, The Roots of the Self: Unraveling the Mystery of Who We Are, HarperCollins, New York, 1995, p. 55. See also Allen L. Hammer, editor, MBTI Applications, chapter written by John Shelton titled “Health, Stress, and Coping,” Oxford Psychologists Press, Oxford, United Kingdom, 1996, pp. 198–200.

8. Debra L. Johnson, Ph.D., et al., “Cerebral Blood Flow and Personality: A Positron Emission Tomography Study,” American Journal of Psychiatry, vol. 156, no. 2, February 1999, pp. 252–257.

9. Daniel Nettle, “The Science Behind Personality,” Independent UK, September 18, 2007, .