Chen, Fengxin, and Zhaojie Zhou. “An H1 -Galerkin Mixed Finite Element Approximation of a Nonlocal Hyperbolic Equation”. Mathematical Modelling and Analysis 22, no. 5 (September 21, 2017): 643-653. Accessed November 14, 2019. https://journals.vgtu.lt/index.php/MMA/article/view/919.