1. Department of Accounting and Finance, Hellenic Mediterranean University, 71005 Heraklion, Greece
2. Department of Mathematics, University of Western Macedonia, 52100 Kastoria, Greece
3. Institute of Applied and Computational Mathematics, Foundation for Research and Technology Hellas (FORTH), 71110 Heraklion, Greece
4. Department of Statistics and Insurance Science, University of Western Macedonia, 52100 Grevena, Greece