1. Department of Mathematics, Shri Vaishnav Institute of Science, Shri Vaishnav Vidyapeeth Vishwavidyalaya, Gram Baroli Sanwer Road, Indore 453331, India
2. Department of Mathematics, Acropolis Institute of Technology & Research, Indore 453771, India
3. Department of Mathematical Sciences and Computing, Walter Sisulu University, Mthatha 5117, South Africa