@article{ETNA_1999__8__a0,
     author = {Gradinaru, V. and Hiptmair, R.},
     title = {Whitney elements on pyramids},
     journal = {Electronic transactions on numerical analysis},
     pages = {154--168},
     publisher = {mathdoc},
     volume = {8},
     year = {1999},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/ETNA_1999__8__a0/}
}