4 IZA Discussion Papers
IZA Discussion Paper No. 7574
IZA Discussion Paper No. 6803
forthcoming in: CESifo Economic Studies
IZA Discussion Paper No. 4489
published in: Scandinavian Journal of Economics, 2012, 114 (4), 1129–1159
IZA Discussion Paper No. 1248
published in: Journal of Human Resources, 2007, 42 (1), 1-31