@article{1183510414, author = {Gottschalk, W. H.}, title = {On $k$-to-1 transformations}, journal = {Bull. Amer. Math. Soc.}, volume = {53}, number = {12}, year = {1947}, pages = { 168-169}, language = {en}, url = {http://dml.mathdoc.fr/item/1183510414} }
Gottschalk, W. H. On $k$-to-1 transformations. Bull. Amer. Math. Soc., Tome 53 (1947) no. 12, pp. 168-169. http://gdmltest.u-ga.fr/item/1183510414/