Du , YuWu , Haijun and Zhang , Zhimin. (2020). Superconvergence Analysis of the Polynomial Preserving Recovery for Elliptic Problems with Robin Boundary Conditions.
            <i>Journal of Computational Mathematics</i>. <i>38</i> (1).
            223-238.
         doi:10.4208/jcm.1911-m2018-0176