Junliang Lv, Guangwei Yuan and Jingyan Yue. (2018). Nonnegativity-Preserving Repair Techniques for the Finite Element Solutions of Degenerate Nonlinear Parabolic Problems.
            <i>Numerical Mathematics: Theory, Methods and Applications</i>. <i>11</i> (3).
            413-436.
         doi:10.4208/nmtma.2017-OA-0125