@article{MZ_1939__44_168824,
     author = {W., Mangler},
     title = {Die {Klassen} von topologischen {Abbildungen} einer geschlossenen {Fl\"ache} auf sich},
     journal = {Mathematische Zeitschrift},
     pages = {541--554},
     publisher = {mathdoc},
     volume = {44},
     year = {1939},
     zbl = {64.0611.03},
     url = {http://geodesic.mathdoc.fr/item/MZ_1939__44_168824/}
}