1. Center for Undergraduate Studies, University of the Punjab, 54590 Lahore, Pakistan
2. School of Mathematics, Minhaj University, 54000 Lahore, Pakistan
3. Department of Mathematics, COMSATS Institute of Information Technology, 54700 Lahore, Pakistan
4. Department of Mathematics, Howard University, Washington, DC-20059, USA
5. School of Electronics and Information Engineering, Wuhan Donghu University, Wuhan-430212, People’s Republic of China
6. Department of Physics and Engineering, Delaware State University, Dover, DE 19901-2277, USA
7. Department of Mathematical Sciences, Delaware State University, Dover, DE 19901-2277, USA
8. Science Program, Texas A and M University at Qatar, P.O. Box 23874, Doha, Qatar