2.643 IZA Discussion Papers
IZA Discussion Paper No. 9
IZA Discussion Paper No. 7
published in: Boesler, Klaus-Achim/ Heinritz, Günter/ Wiessner, Reinhard (Hrsg.), Europa zwischen Integration und Regionalismus, Franz Steiner Verlag, Stuttgart, 1998, 56-66
IZA Discussion Paper No. 2
published in: R. Faini / J. de Melo / K. F. Zimmermann (eds.), Migration. The Controversies and the Evidence, Cambridge, 1999, 296-327