Xiaole Han, Yu Li and Hehu Xie. (2015). A Multilevel Correction Method for Steklov Eigenvalue Problem by Nonconforming Finite Element Methods.
            <i>Numerical Mathematics: Theory, Methods and Applications</i>. <i>8</i> (3).
            383-405.
         doi:10.4208/nmtma.2015.m1334