RATCHAGIT, K. “Asymptotic Stability of a Delay-Difference Control System of Hopfield Neural Networks via Matrix Inequalities and Applications”. Walailak Journal of Science and Technology (WJST), vol. 5, no. 2, Nov. 2011, pp. 191-02, https://wjst.wu.ac.th/index.php/wjst/article/view/89.