@article{MOMA_1981__92_178033,
     author = {Walter Nef},
     title = {Zur {Einf\"uhrung} der {Eulerschen} {Charakteristik.}},
     journal = {Monatshefte f\"ur Mathematik},
     pages = {41--46},
     publisher = {mathdoc},
     volume = {92},
     year = {1981},
     zbl = {0455.51011},
     url = {http://geodesic.mathdoc.fr/item/MOMA_1981__92_178033/}
}