Zhao , Jing-JunXiao , Jing-Yu and Xu , Yang. (2013). Numerical Approximation of Hopf Bifurcation for Tumor-Immune System Competition Model with Two Delays.
            <i>Advances in Applied Mathematics and Mechanics</i>. <i>5</i> (2).
            146-162.
         doi:10.4208/aamm.12-m1224