@article{1077311951,
author = {Ephraim, Robert},
title = {$C^1$ preservation of multiplicity},
journal = {Duke Math. J.},
volume = {43},
number = {1},
year = {1976},
pages = { 797-803},
language = {en},
url = {http://dml.mathdoc.fr/item/1077311951}
}
Ephraim, Robert. $C^1$ preservation of multiplicity. Duke Math. J., Tome 43 (1976) no. 1, pp. 797-803. http://gdmltest.u-ga.fr/item/1077311951/