@article{MZ_1956__64_169580,
     author = {Oskar Herrmann},
     title = {\"Uber den {Rang} der {Schar} der {Spitzenformen} zu {Hilbertschen} {Modulgruppen.}},
     journal = {Mathematische Zeitschrift},
     pages = {457--466},
     publisher = {mathdoc},
     volume = {64},
     year = {1956},
     zbl = {0073.30502},
     url = {http://geodesic.mathdoc.fr/item/MZ_1956__64_169580/}
}