1. Boxer, P., Guerra, N. G., Huesman, L. R., & Morales, J. (2005). Proximal peer-level effects of small group selected prevention on aggression in elementary school children: An investigation of the peer contagion hypothesis. Journal of Abnormal Child Psychology, 33, 325–338.
2. Bronfenbrenner, U. (1979). The ecology of human development: Experiments by nature and by design. Cambridge, MA: Harvard University Press.
3. Bronfenbrenner, U. (1989). Ecological systems theory. In R. Vasta (Ed.), Annals of child development, Vol. 6. Six theories of child development: Revised formulations and current issues (pp. 187–249). London: Jai.
4. Bryant, K. J., Windle, M., & West, S. G. (1997). The science of prevention. Washington, DC: American Psychological Association.
5. Cho, H., Halfors, D., & Sanchez, V. (2005). Evaluation of a high school peer group intervention for at risk youth. Journal of Abnormal Child Psychology, 33, 363–374.