3 IZA Discussion Papers
IZA Discussion Paper No. 10487
published in: Journal of Labor Economics, 2018, 36 (1), 75-120
IZA Discussion Paper No. 6181
for substantially revised version please see IZA DP 10487
IZA Discussion Paper No. 1407
published in: Economic Journal, 2006, 116 (508), 45-83