1. Department of Applied Physics, University of León, 24071 León, Spain
2. School of Economics and Business, University of Ljubljana, 1000 Ljubljana, Slovenia
3. Faculty of Business, Dokuz Eylul University, 35390 Izmir, Turkey
4. Faculty of Economics, University of Gdansk, Bazynskiego 8, 80-309 Gdansk, Poland
5. Faculty of Business and Transport Management, Heilbronn University of Applied Sciences, 74081 Heilbronn, Germany