1. F Cooper, A Khare and U Sukhatme, Phys. Rep. 251, 267 (1995)
2. A N Ikot, L E Akpabio, K Essien, E E Ituen and I B Obot, Electr. J. Chem. 6(1), 113 (2009)
3. S H Dong, Factorization method in quantum mechanics (Springer, Dordrecht, 2007)
4. R Niazian, Afri. Phys. Rev . 4(008), 58 (2010)
5. H Ciftci, R L Hall and N Saad, J. Phys. A36, 11807 (2003)