5 IZA Discussion Papers
IZA Discussion Paper No. 4998
IZA Discussion Paper No. 4309
IZA Discussion Paper No. 1655
published in: Economic Journal, 2006, 116 (509), F10-F28
IZA Discussion Paper No. 1389
published in: Journal of Population Economics, 2007, 20 (3), 621 - 642
IZA Discussion Paper No. 806
published in: International Economic Review, 2003, 44 (4), 1337-1357