1. Department of Mathematics, Government General Degree College, Singur, Hooghly 712 409, West Bengal, India
2. Department of Physics, National Defence Academy, Khadakasla, Pune-411023, India
3. Department of Mathematics, Jadavpur University, Kolkata, West Bengal-700032, India
4. Department of Mathematics, National Defence Academy, Khadak-wasla, Pune-411023, India
5. Department of Mathematics, Budge-Budge Institute of Technology, Budge-Budge, West-Bengal, India