1. Department of Economics and Finance, University of Bari Aldo Moro, 70121 Bari, Italy
2. Faculty of Spatial Economy and Regions in Transition, University of Economics in Katowice, 40-287 Katowice, Poland
3. Faculty of Informatics and Communication, University of Economics in Katowice, 40-287 Katowice, Poland
4. Faculty of Economics, University of Economics in Katowice, 40-287 Katowice, Poland