1. Department of Statistics and Econometrics, The Bucharest University of Economic Studies, 010374 Bucharest, Romania
2. Faculty of Theoretical and Applied Economics, The Bucharest University of Economic Studies, 010374 Bucharest, Romania
3. Department of Cybernetics, Economic Informatics, Finance and Accounting, Petroleum-Gas University, 100520 Ploiesti, Romania
4. Doctoral School of Business Administration, The Bucharest University of Economic Studies, 010374 Bucharest, Romania