@article{BAG_1974__3_138099,
     author = {O.H. Keller},
     title = {Normalformen f\"ur {Fl\"achen} 3. {Ordnung}},
     journal = {Beitr\"age zur Algebra und Geometrie},
     pages = {11--22},
     publisher = {mathdoc},
     volume = {3},
     year = {1974},
     language = {de},
     url = {http://geodesic.mathdoc.fr/item/BAG_1974__3_138099/}
}