3 IZA Discussion Papers
IZA Discussion Paper No. 6185
published in: Journal of Development Economics, 2013, 104, 212-232
IZA Discussion Paper No. 4926
published in: Economics Letters, 2011, 110 (2), 79-82
IZA Discussion Paper No. 4925
published in: E.A. Hanushek, S. Machin, L. Woessmann (eds.), Handbook of the Economics of Education, Vol. 3, pp. 89-200, Amsterdam: North Holland, 2011