Biao Peng,  Chunhua Zhou & Junqiang Ai. (2020). Solution Reconstruction on Unstructured Tetrahedral Meshes Using P<sup>1</sup> -Conservative Interpolation.
            <i>Advances in Applied Mathematics and Mechanics</i>. <i>8</i> (5).
            847-870.
         doi:10.4208/aamm.2015.m1087