1. Department of Mathematics, College of Engineering and Technology, Faculty of Engineering and Technology, SRM Institute of Science and Technology, SRM Nagar, Kattankulathur, 603203 Kanchipuram, Tamil Nadu, India
2. Department of Mathematics, Saveetha School of Engineering, Saveetha Institute of Medical and Technical Sciences, Chennai, 602105 Tamil Nadu, India
3. Department of Mathematics, College of Natural and Applied Sciences, University of Dar es Salaam, Tanzania