1. Department of Mathematics, D.B.S. (P.G.) College (Dehradun), H.N.B. Garhwal Central University, Uttarakhand, India.
2. Applied Science and Humanities Department, Govind Ballabh Pant Institute of Engineering and Technology, Pauri Garhwal, Uttarakhand, India.
3. Department of Mathematics, Government P.G. College, Bazpur, U.S. Nagar, Uttarakhand, India.