2 IZA Discussion Papers
IZA Discussion Paper No. 7926
published in: IZA Journal of European Labor Studies, 3:12, 2014
IZA Discussion Paper No. 666
published in: M. Herfurth, M. Kohli and K. F. Zimmermann (eds.), Arbeit in einer alternden Gesellschaft (Labor in an Aging Society), Leverkusen: Leske+Budrich, 2003, 65-91