@article{1077489100,
author = {Lefschetz, S.},
title = {On critical sets},
journal = {Duke Math. J.},
volume = {1},
number = {1},
year = {1935},
pages = { 392-412},
language = {en},
url = {http://dml.mathdoc.fr/item/1077489100}
}
Lefschetz, S. On critical sets. Duke Math. J., Tome 1 (1935) no. 1, pp. 392-412. http://gdmltest.u-ga.fr/item/1077489100/