Pons, R.-M., M. D. Prieto, C. Lomeli, M. R. Bermejo, and S. Bulut. “Cooperative Learning in Mathematics: A Study on the Effects of the Parameter of Equality on Academic Performance”. Anales De Psicología / Annals of Psychology, Vol. 30, no. 3, Aug. 2014, pp. 832-40, doi:10.6018/analesps.30.3.201231.