1. Assistant Professor, Dept. of Mathematics, Comsats Institute of Information Technology, Wah Cantt 47040, Pakistan (corresponding author).
2. Professor, Dept. of Mathematics, Quaid-I-Azam Univ., Islamabad 45320, Pakistan.
3. Associate Professor, Nonlinear Analysis and Applied Mathematics (NAAM) Research Group, Dept. of Mathematics, Faculty of Science, King Abdulaziz Univ., P.O. Box 80203, Jeddah 21589, Saudi Arabia.