1. Alieva, L. V., Nefedova, N. A., & Rudenko, I. V. (2014). Theoretical bases and principles of extracurricular activities as an innovative unit of the university educational system. Moscow: International Independent Ecological and Political University Press. (in Russian).
2. Bakoban, R. A., & Aljarallah S. A. (2015). Extracurricular activities and their effect on the student’s grade point average: Statistical study. Educational Research and Reviews, 10(20), 2737-2744. doi:10.5897/ERR2015.2436.
3. Bartkus, K. R., Nemelka, B., Nemelka, M., & Gardner, Ph. (2012). Clarifying the Meaning of Extracurricular Activity: A Literature Review of Definitions. American Journal of Business Education, 5(6), 693-703. doi:10.19030/ajbe.v5i6.7391.
4. Belikova, L. F. (2002). Students’ attitudes toward extracurricular activity in an institution of higher learning. Russian Education and Society, 44(2), 73-85. (in Russian).
5. Cheng, D. X., & Zhao, Ch. M. (2006). Cultivating Multi-cultural Competence through Active Participation: Extracurricular Activities and Multi-cultural Learning. NASPA Journal, 43(4), 13-38. EJ751049.