Hossain, F., and S. Das. “DEVELOPMENT OF FOKKINK-FOKKINK-WANG’S GENERATING FUNCTION FOR FFW(n)”. International Journal of Research -GRANTHAALAYAH, vol. 3, no. 2, Feb. 2015, pp. 69-76, doi:10.29121/granthaalayah.v3.i2.2015.3041.