@article{MZ_1977__154_172523,
     author = {G\"unter T\"orner},
     title = {(rn-1, r) {Hjelmslev-Ebenen} des {Typs} n.},
     journal = {Mathematische Zeitschrift},
     pages = {189--202},
     publisher = {mathdoc},
     volume = {154},
     year = {1977},
     zbl = {0336.05015},
     url = {http://geodesic.mathdoc.fr/item/MZ_1977__154_172523/}
}