@article{MAN_1930__103_159426,
     author = {H. Kneser},
     title = {Die kleinste {Bedeckungszahl} innerhalb einer {Klasse} von {Fl\"achenabbildungen}},
     journal = {Mathematische Annalen},
     pages = {347--358},
     publisher = {mathdoc},
     volume = {103},
     year = {1930},
     zbl = {56.1130.02},
     url = {http://geodesic.mathdoc.fr/item/MAN_1930__103_159426/}
}