1. Department of Mathematics, School of Science, University of Management and Technology, C-II Johar Town, Lahore 54770, Pakistan
2. Institute for Groundwater Studies (IGS), University of the Free State Bloemfotain, South Africa
3. Department of Mathematics, Government College University Lahore, Lahore,54000, Pakistan
4. Department of Mathematics, Riphah International University, QIE Township, Lahore 54000, Pakistan
5. School of Mathematics and Information Science, Henan Polytechnic University, Jiaozuo, China