4 IZA Discussion Papers
IZA Discussion Paper No. 16946
IZA Discussion Paper No. 8316
published in: Journal of Labor Economics, 2017, 35 (4), 993-1030.
IZA Discussion Paper No. 3310
published in: Journal of Human Capital, 2008, 2(1), 1-31
IZA Discussion Paper No. 1700
published in: E. Hanushek and F. Welch, eds., Handbook of the Economics of Education, North Holland: Amsterdam, 2006, 307-458