Kumar, Arun, and G. V. Prasad. 1989. “A Necessary Condition for (F<sub>1</sub>-Effectiveness of(C, L) (N,p<sub>n</Sub>) Method”. The Journal of the Indian Mathematical Society 54 (1-4):139-46. https://informaticsjournals.co.in/index.php/jims/article/view/21881.