1. Department of Economics; Second University of Naples; Capua Italy
2. Department of Economics and Statistics; University of Naples Federico II; Naples Italy
3. Ceris-CNR; Turin Italy
4. Department of Economics; University of Perugia; Perugia Italy
5. Centro Studi Luca d'Agliano; Milan Italy
6. Halle Institute of Economic Research (IWH); Halle Germany