Syamsuddin, T., M. H. Abu Hassan, F. Ismai, and L. W.J. “Stability Analysis and Maximum Profit of One Prey-Two Predators Model under Constant Effort of Harvesting”. Malaysian Journal of Science, vol. 26, Dec. 2007, pp. 43-51, http://mjs.um.edu.my/index.php/MJS/article/view/8725.