Institution: | 1. Department of Economics, Babe?–Bolyai University, 400591 Cluj-Napoca, Romania;2. Institute of Applied Mathematics, John von Neumann Faculty of Informatics, Óbuda University, 1034 Budapest, Hungary;3. Department of Mathematics, University of Osijek, 31000 Osijek, Croatia;4. Faculty of Maritime Studies, University of Rijeka, 51000 Rijeka, Croatia;5. Department of Mathematics and Informatics, Sapientia Hungarian University of Transylvania, 540485 Târgu-Mure?, Romania |