To know more about this work please contact :

Maria Cristina Recchioni, Dipartimento di Management, UniversitÓ Politecnica delle Marche, Piazzale Martelli 8, 60121 Ancona, Italy, Phone: +39-071-2207066, Fax:+39-071-2207150,

e-mail:  m.c.recchioni@univpm.it