Prasad, B. Hari, and N. Ch. Pattabhi Ramacharyulu. “On the Stability of a Four Species Syn Eco-System With Commensal Prey-Predator Pair With Prey-Predator Pair of Hosts-VI (Normal Steady State)”. MATEMATIKA, vol. 28, Nov. 2012, pp. 181-92, doi:10.11113/matematika.v28.n.573.