1. Department of Mathematics, School of Physical and Decision Sciences, Babasaheb Bhimrao Ambedkar University, (A Central University), Lucknow, UP, India
2. Department of Mathematics, Institute of natural sciences and humanities, Shri Ramswaroop, Memorial University, Tindola, Lucknow, India
3. Department of Mathematics, University Institute of Sciences, Chandigarh University, Mohali, Punjab, India