1. Allison, P. D. (2009). Fixed effects regression models. Thousand Oaks, CA: Sage.
2. Baumeister, R. F., & Leary, M. R. (1995). The need to belong: Desire for interpersonal attachments as a fundamental human motivation. Psychological Bulletin,
117(3), 497–529.
3. Bean, J., & Eaton, S. (2000). A psychological model of college student retention. In J. M. Braxton (Ed.), Reworking the student departure puzzle (pp. 48–61). Nashville, TN: Vanderbilt University Press.
4. New directions for student services;M Benjamin,2007
5. Blanc, R. A., Debuhr, L. E., & Martin, D. C. (1983). Breaking the attrition cycle: The effects of supplemental instruction on undergraduate performance and attrition. Journal of Higher Education,
54(1), 80–90.