3 IZA Discussion Papers
IZA Discussion Paper No. 7560
IZA Discussion Paper No. 3797
published in: Labour Economics, 2010, 17 (1), 170-179
IZA Discussion Paper No. 139
published in: Jahrbücher für Nationalökonomie und Statistik, 2008, 228 (5-6), 446-464, (Special Issue: Labormetrics)