1. Department of Mathematics, K L University, Vaddeswaram, Andhra Pradesh 522502, India
2. Department of Mathematics, Acharya Nagarjuna University, Andhra Pradesh 522 510, India
3. Department of Mathematics, Vijaya College of Engineering, Khammam, Telangana 507 305, India
4. Department of Mathematics, Nepal Sanskrit University, Valmeeki Campus, Exhibition Road, Kathmandu 44500, Nepal