Mingxia Li, Xiaofei Guan & Shipeng Mao. (1970). Convergence and Superconvergence Analysis of Lagrange Rectangular Elements with Any Order on Arbitrary Rectangular Meshes.
            <i>Journal of Computational Mathematics</i>. <i>32</i> (2).
            169-182.
         doi:10.4208/jcm.1310-FE2