1. Department of Mathematics, Dyal Singh College, University of Delhi, Lodhi Road, New Delhi-110003, India.
2. Department of Mathematics, School of Basic Sciences & Research, Sharda University, Greater Noida-201306, Uttar Pradesh, India. Noida Institute of Engineering & Technology, Greater Noida, Uttar Pradesh, India.
3. Department of Mathematical and Physical Science, School of Computer Science, University of Nizwa, Sultanate of Oman.
4. Department of Mathematics, School of Basic Sciences & Research, Sharda University, Greater Noida-201306, Uttar Pradesh, India.
5. Department of Mathematics, J. C. Bose, University of Science and Technology, YMCA Faridabad-121006, Haryana, India.