1. Department of Mathematics, Central University of Karnataka, Kalaburagi, India. E-mail: dr.nsrh@gmail.com
2. Department of Mathematics, VIT University, Vellore, India. E-mail: gkumaranmsc31@gmail.com
3. Department of Mathematics, College of Sciences, King Khalid University, Abha, Saudi Arabia. E-mail: saakhtar@kku.edu.sa