1. Faculty of Economics and Law, Kore University of Enna , Cittadella Universitaria, Enna 94100, Italy . e-mail: giovanni.bonaccolto@unikore.it ; e-mail: giuseppina.talamo@unikore.it
2. Department of Economics and Management, University of Padua , Via del Santo 33, Padova 35123, Italy . e-mail: giulio.pedrini@unikore.it