P. Srimanchari, M. Saroja and M. Venkatachalam
Information Technology Journal 12 ( 7 ): 1279 - 1288 , 2013
M. Venkatachalam, N. Mohanapriya and J. Vernold Vivin
Journal of Modern Mathematics and Statistics 5 ( 1 ): 33 - 36 , 2011