@article{1077472368, author = {Whyburn, G. T.}, title = {Homotopy reductions of mappings into the circle}, journal = {Duke Math. J.}, volume = {11}, number = {1}, year = {1944}, pages = { 35-42}, language = {en}, url = {http://dml.mathdoc.fr/item/1077472368} }
Whyburn, G. T. Homotopy reductions of mappings into the circle. Duke Math. J., Tome 11 (1944) no. 1, pp. 35-42. http://gdmltest.u-ga.fr/item/1077472368/