1. Department of Mathematics, University of Poonch Rawalakot, Azad Kashmir, Pakistan
2. Department of Mathematics Texas A& M University-Kingsville 700 University Blvd., MSC 172 Kingsville, Texas 78363-8202 USA
3. Universit'e de Sousse, Institut Superieur d'Informatique et des Techniques de Communication, H. Sousse 4000, Tunisia
4. China Medical University Hospital, China Medical University, Taichung 40402, Taiwan
5. Department of Mathematics and Applied Mathematics, Sefako Makgatho Health Sciences University, Ga-Rankuwa, South Africa
6. Institute of Research and Development of Processes IIDP, University of the Basque Country, Campus of Leioa, PO Box 48940, Leioa, Bizkaia 48940, Spain