1. Department of Economics , Kozminski University , Jagiellońska Street, 57/59, 03301 Warsaw , Poland
2. Department of Economics and Management , University of Pisa , Via Cosimo Ridolfi, 10, I–56124 Pisa (PI) , Italy
3. Department of Law , University of Pisa , Via Collegio Ricci, 10, I–56126 Pisa (PI) , Italy