@article{MZ_1978__163_172760,
     author = {Joachim Assion},
     title = {Einige endliche {Faktorgruppen} der {Zopfgruppen.}},
     journal = {Mathematische Zeitschrift},
     pages = {291--302},
     year = {1978},
     volume = {163},
     zbl = {0407.20030},
     url = {http://geodesic.mathdoc.fr/item/MZ_1978__163_172760/}
}