@article{1029004393,
author = {Norton, Alec and Pugh, Charles},
title = {Critical sets in the plane.},
journal = {Michigan Math. J.},
volume = {38},
number = {1},
year = {1991},
pages = { 441-459},
language = {en},
url = {http://dml.mathdoc.fr/item/1029004393}
}
Norton, Alec; Pugh, Charles. Critical sets in the plane.. Michigan Math. J., Tome 38 (1991) no. 1, pp. 441-459. http://gdmltest.u-ga.fr/item/1029004393/