1. Quantitative Methods and Information Systems Department, Faculty of Economics, Matej Bel University in Banská Bystrica, Banská Bystrica, Slovak Republic
2. Mathematics Department, Faculty of Natural Sciences, Jan Evangelista Purkyně University in Ústí nad Labem, Ústí nad Labem, Czech Republic
3. Economics Department, Faculty of Economics, Matej Bel University in Banská Bystrica, Banská Bystrica, Slovak Republic