1. Department of Mathematics, School of Applied and Life Sciences, Uttaranchal University, Dehradun 248007, India
2. Department of Mathematics, Graphic Era Hill University, Bhimtal 263136, India
3. School of Computer Science, University of Petroleum & Energy Studies, Dehradun 248007, India
4. Center for Research and Development in Mathematics and Applications (CIDMA), Department of Mathematics, University of Aveiro, 3810-193 Aveiro, Portugal