1. Department of Allied Sciences, Graphic Era Hill University, Haldwani 263139, Uttarakhand, India
2. Department of Mathematics, Graphic Era Hill University, Bhimtal 263132, Uttarakhand, India
3. Department of Mathematics, Graphic Era Deemed to be University, Dehradun 248002, Uttarakhand, India
4. Department of Mathematics, KIET Group of Institutions, Delhi-NCR, Ghaziabad 201206, India