685 IZA Discussion Papers
IZA Discussion Paper No. 87
published in: Economics of Education Review, 2002, 21 (2), 221-229
IZA Discussion Paper No. 60
IZA Discussion Paper No. 58
IZA Discussion Paper No. 42
published in: Journal of Human Resources, 2001, 36 (1), 1-30
IZA Discussion Paper No. 19
published in: Journal of Population Economics 2000, 13 (1), 57-79