1. Department of Basic Sciences, University of Engineering and Technology Peshawar, Khyber Pakhtunkhwa, Pakistan
2. Department of Mathematics and Statistics, University of Swat, Khyber Pakhtunkhawa, Pakistan
3. Department of Mathematics, Faculty of Science, King Mongkut's University of Technology Thonburi (KMUTT), 126 Pracha-Uthit Road, Bang Mod, Thrung Khru, Bangkok 10140, Thailand
4. Siirt University, Art and Science Faculty of Science, Department of Mathematics, TR-56100 Siirt, Turkey