1. Department of Mathematics, Hooghly Engineering and Technology College , Vivekananda Road, Hooghly - 712103 , India
2. Department of Mathematics, Gobardanga Hindu College , 24-Parganas (N), Pin- 743273 , India
3. Department of Applied Mathematics , University of Calcutta , 92, A. P. C. Road, Kolkata - 700009 , India