1[1]Johnson D.W., & Johnson R., Learning together and alone: cooperation, competition and individualization (3rd ed.), Engliwood Cliffs, NJ: Prentice Hall. (1991)
2[3]Neil Davidson, Cooperative and Collaborative learning: an interactive perspective, in Jacqueline S. Thousand et al. (eds.), Creative and Collaborative Learning, Paul H. Brookers Publishing Co. Inc., 1994
