1. The Faculty of Economic Cybernetics, Statistics and Informatics, The Bucharest University of Economic Studies, 15-17 Dorobanti Street, Sector 1, 010552 Bucharest, Romania
2. The National Scientific Research Institute for Labour and Social Protection, 6-8 Povernei Street, 010643 Bucharest, Romania
3. The Faculty of Theoretical and Applied Economics, The Bucharest University of Economic Studies, 15-17 Dorobanti Street, Sector 1, 010552 Bucharest, Romania