1. Department of Mathematics, Guru Ghasidas Vishwavidyalaya, Bilaspur 495009, India
2. Department of Mathematical Sciences, College of Sciences, Princess Nourah bint Abdulrahman University, Riyadh 11546, Saudi Arabia
3. Section of Mathematics, Department of Information Technology, University of Technology and Applied Sciences, P.O. Box 77, Shinas 324, Oman