Hwong، N.؛ Caswell، A.؛ Johnson، D.W.؛ Johnson، R. (199). "Effects of cooperative and individualistic learning on prospective elementary teachers' music achievement and attitudes". Journal of Social Psychology. ج. 133 ع. 1: 53–64. DOI:10.1080/00224545.1993.9712118. PMID:8464219.
Hwong، N.؛ Caswell، A.؛ Johnson، D.W.؛ Johnson، R. (199). "Effects of cooperative and individualistic learning on prospective elementary teachers' music achievement and attitudes". Journal of Social Psychology. ج. 133 ع. 1: 53–64. DOI:10.1080/00224545.1993.9712118. PMID:8464219.