603 IZA Discussion Papers
IZA Discussion Paper No. 55
published in: Jahrbücher für Nationalökonomie und Statistik, 1999, 219 (3/4), 308-325
IZA Discussion Paper No. 41
published in: Swedish Economic Policy Review, 1998, 5(2), 303-343
IZA Discussion Paper No. 26
published in: Journal of Economic Literature, 2000, 38 (1), 77-114