Buss, D. M. 2000. The evolution of happiness // American Psychologist 55: 15–21.

Begley, Sharon, and Jean Chatzky. 2011, October 30. The new science behind your spending addiction // Newsweek; Casey, B. J., Leah H. Somerville, Ian H. Gotlib, Ozlem Ayduk, Nicholas T. Franklin, Mary K. Askren, John Jonides, et al. 2011. Behavioral and neural correlates of delay of gratification 40 years later // Proceedings of the National Academy of Sciences 108: 14998–15003.