Druckman, D. (2004). Be All That You Can Be: Enhancing Human Performance. Journal of Applied Social Psychology, 34:11, pp. 2234 – 2260. DOI:10.1111/j.1559-1816.2004.tb01975.x
Richards, J.C. and Rodgers, T.S. (2001). Approaches and Methods in Language Teaching (2nd ed.). Cambridge: Cambridge University Press, ISBN 0-521-00843-3, (стр.100 – 107)
