Hongqiang Lu & Qiang Sun. (1970). A Straightforward $hp$-Adaptivity Strategy for Shock-Capturing with High-Order Discontinuous Galerkin Methods.
            <i>Advances in Applied Mathematics and Mechanics</i>. <i>6</i> (1).
            135-144.
         doi:10.4208/aamm.2013.m-s1