1. Department of Mathematics, School of Physical Sciences, DIT University, Dehradun, Uttarakhand 248 009, India
2. Department of Mathematics & Computing, Indian Institute of Technology (ISM), Dhanbad 826 004, Jharkhand, India
3. Mharat Academy for Training & Development, Ibb, Yemen
4. Department of Mathematics and Statistics, College of Science, Taif University, P.O. Box 11 099, Taif 21 944, Saudi Arabia
5. Department of Physics, College of Science, King Khalid University, PO Box 9004, Abha 61 413, Saudi Arabia