| Affiliation: | 1. Department of Mathematics and Statistics, University of Cyprus, Nicosia, 1678, Cyprus;2. Department of Mathematics, Cornell University, Ithaca, NY 14853-4201, USA;1. Dipartimento di Matematica e Fisica “E. De Giorgi”, Università del Salento – C.P.193, I-73100 Lecce, Italy;2. Instituto Universitario de Matemática Pura y Aplicada IUMPA, Universitat Politècnica de València, E-46071 Valencia, Spain;3. Math.-Geogr. Fakultät, Katholische Universität Eichstätt-Ingolstadt, D-85072 Eichstätt, Germany |
