1. Department of Computer Engineering , Czestochowa University of Technology , al. Armii Krajowej 36, 42-200 Częstochowa , Poland
2. Management Department , University of Social Sciences , 90-113 Łódź
3. Clark University Worcester, MA 01610, USA
4. Information Technology Institute , University of Social Sciences , 90-113 Łódź
5. Meiji University , Tama-ku, Kawasaki, 214-8571 Japan