@article{MAN_1933__108_159639,
     author = {K. Borsuk and St. Ulam},
     title = {\"Uber gewisse {Invarianten} der {e-Abbildungen}},
     journal = {Mathematische Annalen},
     pages = {311--318},
     publisher = {mathdoc},
     volume = {108},
     year = {1933},
     zbl = {0006.32901},
     url = {http://geodesic.mathdoc.fr/item/MAN_1933__108_159639/}
}