Worchel, Stephen, Virginia A. Andreoli, and Robert Folger. 1977. “Intergroup Cooperation and Intergroup Attraction: The Effect of Previous Interaction and Outcome of Combined Effort”. Journal of Experimental Social Psychology 13: 131-40. doi:10.1016/S0022-1031(77)80006-1.

Browna, Rupert. 1984. “The Effects of Intergroup Similarity and Cooperative Vs Competitive Orientation on Intergroup Discrimination”. British Journal of Social Psychology 23: 21-33. doi:10.1111/j.2044-8309.1984.tb00605.x.

Bettencourt, B.Ann, Marilynn B Brewer, Marian Rogers Croak, and Norman Miller. 1992. “Cooperation and the Reduction of Intergroup Bias: The Role of Reward Structure and Social Orientation”. Journal of Experimental Social Psychology 28: 301-19. doi:10.1016/0022-1031(92)90048-O.

Lamoreaux, Marika J. 2008. “Reducing Intergroup Bias: When Contact Is Instrumental for Achieving Group Goals”. University of Delaware. Referenced from search.proquest.com: Reducing intergroup bias: When contact is instrumental for achieving group goals.