1. Department of Engineering Mathematics, Koneru Lakshmaiah Education Foundation, Guntur, Andhra Pradesh, India
2. Department of Mathematics, Amrita School of Physical Science, Amrita Vishwa Vidyapeetham, Coimbatore 641112, Tamilnadu, India
3. Department of Mathematics, Cauvery College for women, Tiruchirappalli, Tamilnadu, India
4. Department of Mathematics, School of Science, Walailak University, Thasala, Nakhon Si Thammarat 80160, Thailand