@article{1077491745,
author = {Roberts, J. H.},
title = {Two-to-one transformations},
journal = {Duke Math. J.},
volume = {6},
number = {1},
year = {1940},
pages = { 256-262},
language = {en},
url = {http://dml.mathdoc.fr/item/1077491745}
}
Roberts, J. H. Two-to-one transformations. Duke Math. J., Tome 6 (1940) no. 1, pp. 256-262. http://gdmltest.u-ga.fr/item/1077491745/