1. Department of Mathematics, College of Science, University of Ha’il, Ha’il P.O. Box 2240, Saudi Arabia
2. Department of Mathematics, Faculty of Science, University of Gujrat, Gujrat 50700, Pakistan
3. Section of Mathematics, International Telematic University Uninettuno, Corso Vittorio Emanuele II, 39, 00186 Roma, Italy
4. Department of Mathematics, Faculty of Science, Mansoura University, Mansoura 35516, Egypt