Voir la notice de l'article provenant de la source European Digital Mathematics Library
@article{CMH_1938__11_138716, author = {H. Hopf and M. Rueff}, title = {\"Uber faserungstreue {Abbildungen} der {Sph\"aren.}}, journal = {Commentarii mathematici Helvetici}, pages = {49--61}, publisher = {mathdoc}, volume = {11}, year = {1938}, zbl = {0019.37204}, url = {http://geodesic.mathdoc.fr/item/CMH_1938__11_138716/} }
H. Hopf; M. Rueff. Über faserungstreue Abbildungen der Sphären.. Commentarii mathematici Helvetici, Tome 11 (1938), pp. 49-61. http://geodesic.mathdoc.fr/item/CMH_1938__11_138716/