“A Simple Explanation of Superconvergence for Discontinuous Galerkin Solutions to $\boldsymbol{u_t}$+$\boldsymbol{u_x}$=0”, Commun. Comput. Phys., vol. 21, no. 4, pp. 905–912, Apr. 2018, doi: 10.4208/cicp.OA-2016-0052.