1Faculty of Economics and Management, University of Zielona Gora, Licealna 9, 65-417 Zielona Gora, Poland
2Wroclaw University of Economics, Komandorska 118/120, 53-345 Wroclaw, Poland
Submission date: 2015-03-16
Final revision date: 2015-07-23
Acceptance date: 2015-07-23
Publication date: 2015-11-27
Pol. J. Environ. Stud. 2015;24(6):2381–2385