@article{MAN_1973__205_162487,
     author = {H. Helling},
     title = {Note \"uber das {Geschlecht} gewisser arithmetischer {Gruppen.}},
     journal = {Mathematische Annalen},
     pages = {173--180},
     publisher = {mathdoc},
     volume = {205},
     year = {1973},
     zbl = {0245.10014},
     url = {http://geodesic.mathdoc.fr/item/MAN_1973__205_162487/}
}