Peterson, C., y Seligman, M. (2004). Character strengths and virtues: A handbook and classification. Estados Unidos: American Psychological Association.
Park, N., Peterson, C., y Seligman, M. (2006). Character strengths in fifty-four nations and the fifty US states. The Journal of Positive Psychology. Recuperado de https://doi.org/10.1080/17439760600619567