@article{JRAM_1927__157_149622,
     author = {Ludwig Bieberbach},
     title = {Eine hinreichende {Bedingung} f\"ur schlichte {Abbildungen} des {Einheitskreises.}},
     journal = {Journal f\"ur die reine und angewandte Mathematik},
     pages = {189--192},
     publisher = {mathdoc},
     volume = {157},
     year = {1927},
     zbl = {53.0322.02},
     url = {http://geodesic.mathdoc.fr/item/JRAM_1927__157_149622/}
}