5 IZA Discussion Papers
IZA Discussion Paper No. 14880
IZA Discussion Paper No. 14670
IZA Discussion Paper No. 9915
IZA Discussion Paper No. 6315
published in: American Economic Journal: Economic Policy, 2014, 6 (4), 135-173
IZA Discussion Paper No. 2111
published in: Quarterly Journal of Economics, 2007, 122 (1), 159-208