@article{MZ_1983__182_173261,
     author = {Rainer L\"owen},
     title = {Stable {Planes} with {Isotropic} {Points.}},
     journal = {Mathematische Zeitschrift},
     pages = {49--62},
     publisher = {mathdoc},
     volume = {182},
     year = {1983},
     zbl = {0506.51012},
     url = {http://geodesic.mathdoc.fr/item/MZ_1983__182_173261/}
}