1. Department of Mathematics, Khwaja Fareed University of Engineering and Information Technology, Rahim Yar Khan, Pakistan
2. Department of Mathematics, Virtual University of Pakistan, Lahore, Pakistan
3. School of Mathematics, Northwest University, Xian, People's Republic of China
4. Department of Mathematics, University of Management and Technology, Lahore, Pakistan
5. Department of Applied Mathematics, Northwestern Polytechnical University, Xian, People's Republic of China
6. Faculty of Computer Science and Information Technology, Superior University, Lahore, Pakistan