4 IZA Discussion Papers
IZA Discussion Paper No. 8736
published in: Empirical Economics, 2015, 48, 227-251
IZA Discussion Paper No. 5662
published in: Economics of Education Review, 2011, 30 (6), 1202-1214
IZA Discussion Paper No. 2650
published in: Annales d'Economie et de Statistique, 2008, 92/92, 427 - 451