Solin , PavelDubcova , Lenka and Dolezel , Ivo. (2010). Adaptive $hp$-FEM with Arbitrary-Level Hanging Nodes for Maxwell's Equations.
            <i>Advances in Applied Mathematics and Mechanics</i>. <i>2</i> (4).
            518-532.
         doi:10.4208/aamm.10-m1012