@article{MZ_1929__29_168090,
     author = {Heinz Hopf},
     title = {\"Uber die algebraische {Anzahl} von {Fixpunkten.}},
     journal = {Mathematische Zeitschrift},
     pages = {493--524},
     publisher = {mathdoc},
     volume = {29},
     year = {1929},
     zbl = {55.0970.02},
     url = {http://geodesic.mathdoc.fr/item/MZ_1929__29_168090/}
}