Chunjae Park Dongwoo Sheen <i>P</i><sub>1</sub>-Nonconforming Quadrilateral Finite Element Methods for Second-Order Elliptic Problems. 624-640 2003 41 SIAM J. Numerical Analysis 2 http://dx.doi.org/10.1137/S0036142902404923 db/journals/siamnum/siamnum41.html#ParkS03