@article{MZ_1977__154_172521,
     author = {Karl Erich Wolff},
     title = {Eine {Charakterisierung} der (i, {j)-Pl\"ane.}},
     journal = {Mathematische Zeitschrift},
     pages = {169--174},
     publisher = {mathdoc},
     volume = {154},
     year = {1977},
     zbl = {0336.05019},
     url = {http://geodesic.mathdoc.fr/item/MZ_1977__154_172521/}
}