4 IZA Discussion Papers
IZA Discussion Paper No. 6935
published in: Economic Letters, 2013, 118(1), 192-194
IZA Discussion Paper No. 5181
published in: Labour Economics, 2013, 21, 42-58
IZA Discussion Paper No. 2401
IZA Discussion Paper No. 1717
published in: IZA Journal of Labor Economics, 2015, 4:16