@article{MZ_1966__91_170507,
     author = {H.C. Wilkie},
     title = {On {non-Euclidean} crystallographic groups.},
     journal = {Mathematische Zeitschrift},
     pages = {87--102},
     publisher = {mathdoc},
     volume = {91},
     year = {1966},
     zbl = {0166.02602},
     url = {http://geodesic.mathdoc.fr/item/MZ_1966__91_170507/}
}