1. Department of Environmental Science, Quaid I Azam University, Islamabad, Pakistan
2. Department of Mathematics, College of Sciences and Arts (Muhyil), King Khalid University, Muhyil, Saudi Arabia
3. Department of Mathematics and Computer, College of Sciences, Ibb University, Ibb, Yemen
4. Department of Statistics, Quaid I Azam University, Islamabad, Pakistan
5. Department of Community Medicine, Wah Medical College, National University of Medical Sciences, Pakistan
6. Mathematics Department, Prince Sattam Bin Abdulaziz University, Al-Kharj, Saudi Arabia
7. Department of Statistics and Information, Sana’a University, Sana’a, Yemen