83 IZA Discussion Papers
IZA Discussion Paper No. 1691
published in: B.E. Journal of Economic Analysis and Policy: Contributions to Economic Analysis and Policy, 2006, 5 (2), Article 2
IZA Discussion Paper No. 1641
published in: American Economic Review, 2005, 95 (2), 346-351
IZA Discussion Paper No. 1417
revised version published in: Journal of Labor Economics, 2007, 25 (4), 693-723