1. Department of Mathematics and Geosciences, University of Trieste, Via Weiss 2, 34128 Trieste, Italy
2. Ev—K2—CNR Committee, Via San Bernardino 145, 24126 Bergamo, Italy
3. COMSAT, University of Science and Technology, Park Road, Chak Shahzad, Islamabad, Pakistan
4. TeleGIs Laboratory, Department of Chemistry and Geology, University of Cagliari, via Trentino 51, 09127 Cagliari, Italy