Tian-Xiao Zhou, Shou-Li Li, Zheng-Wei Wang, Jian-Min Xing and Ping Yang. (1983). Fourteen-Node Mixed Stiffness Element and Its Computational Comparisons with Twenty-Node Isoparametric Element.
            <i>Journal of Computational Mathematics</i>. <i>1</i> (2).
            182-194.
         doi: