* Peterson, Christopher, & Seligman, Martin E. P. (2004). ''Character Strengths and Virtues''. Oxford: Oxford University Press. ISBN 987-0-19-516701-6 | * Peterson, Christopher, & Seligman, Martin E. P. (2004). ''Character Strengths and Virtues''. Oxford: Oxford University Press. ISBN 987-0-19-516701-6 |