1. Department of Mathematics, GITAM University, Hyderabad campus, Rudraram, Medak 502329, Telangana, India
2. Department of Mathematics, Faculty of Science and Technology, IFHE University, Dontanapalli, Hyderabad 501203, Telangana, India
3. Department of Mathematics, National Institute of Technology Puducherry, Karaikal, Puducherry, India 609 609