1. Barber, B.L., Eccles, S.J. & Stone, M.R. (2001). Whatever Happened to the Jock, the Brain and the Princess? Young Adult Pathways Linked to Adolescent Activity Involvement and Social Identity. Journal of Adolescent Research, 16(5): 429-455
2. Bogdan, R.C. & Biklen, S.K. (2003). Qualitative Research for Education: An introduction to Theories and. Methods (4th ed.). New York: Pearson Education
3. Buyukoztiirk, Ş., Çakmak, K.E., Akgiin E.O., Karadeniz, Ş. & Demirel F. (2008). BilimselArasttrma Yontemleri, Pegem Akademi Yayinevi, Ankara
4. Cooper, H., Valentine, J.C., Nye, B. & Lindsay, J.J. (1999). Relationship between five after-school activities and academic achievement. Journal of Educational Psychology, 91(2): 369-378
5. Creswell, J. (2002). Educational research: Planning, conducting, and evaluating quantitative and qualitative research (2nd ed.). NJ, New