@article{NUMA_1990__58_5_133502,
     author = {Ricardo Dur\'an},
     title = {Superconvergence for rectangular mixed finite elements.},
     journal = {Numerische Mathematik},
     pages = {287--298},
     publisher = {mathdoc},
     volume = {58},
     number = {5},
     year = {1990},
     zbl = {0691.65076},
     url = {http://geodesic.mathdoc.fr/item/NUMA_1990__58_5_133502/}
}