27.
Pelletier, L. G., Tuson, K. M., Fortier, M. S., Vallerand, R. J., Briere, N. M., & Blais, M. R. (1995). Toward a new measure of intrisic motivation, extrinsic motivation, and amotivation in sports: The Sport Motivation Scale (SMS). Journal of sport and Exercise Psychology, 17, 35–53.