1. Angist, J. D. and Pischke, J. S. (2009). Mostly Harmless Econometrics: An Empiricist’s Companion. New Jersey: Princeton University Press.
2. Bae, S., Kim, S., Yang, S. (2010). The Relationship between After-school Participation and Students’ Private Tutoring Expenses and Academic Achievement. The Journal of Educational Administration, 28(2), 55-79.
3. Baek, B (2012). The Effects of Extra-curricular Activities in or out on School on the Middle School Students’ School Adjustment and Value Awareness of School. The Korea Educational Review, 18(1), 143-167.
4. Baik, I. W. (2009). Economics of Education. Seoul: Hakjisa.
5. Brewer, D. J., Hentschke, G. C., and Eide, E. R. (2010). Theoretical Concepts in the Economics of Education. In Brewer, D. J. and McEwan, P. J. (eds) Economics of Education, pp 3-8. Oxford: Elsevier.