A class of nonparametric DSSY nonconforming quadrilateral elements Youngmok Jeon, Hyun Nam, Dongwoo Sheen and Kwangshin Shim ESAIM: M2AN, 47 6 (2013) 1783-1796 Published online: 07 October 2013 DOI: 10.1051/m2an/2013088