1. Department of Sciences of Agriculture, Food, Natural Resources and Engineering, University of Foggia, Via Napoli, 25, 71121 Foggia, Italy
2. Italian National Group of Mathematical Physics (GNFM) of the Italian National Institute of High Mathematics (INDAM), 00185 Rome, Italy
3. Department of Mechanics, Mathematics and Management (DMMM), Politecnico di Bari, Via Orabona, 4, 70125 Bari, Italy