@article{1077467078,
author = {Levin, J. J.},
title = {Singular perturbations of nonlinear systems of differential
equations related to conditional stability},
journal = {Duke Math. J.},
volume = {23},
number = {1},
year = {1956},
pages = { 609-620},
language = {en},
url = {http://dml.mathdoc.fr/item/1077467078}
}
Levin, J. J. Singular perturbations of nonlinear systems of differential
equations related to conditional stability. Duke Math. J., Tome 23 (1956) no. 1, pp. 609-620. http://gdmltest.u-ga.fr/item/1077467078/