@article{1250130390,
author = {Ladde, G.S. and Lakshmikanthan, V. and Leela, S.},
title = {A technique in perturbation theory},
journal = {Rocky Mountain J. Math.},
volume = {6},
number = {4},
year = {1976},
pages = { 133-140},
language = {en},
url = {http://dml.mathdoc.fr/item/1250130390}
}
Ladde, G.S.; Lakshmikanthan, V.; Leela, S. A technique in perturbation theory. Rocky Mountain J. Math., Tome 6 (1976) no. 4, pp. 133-140. http://gdmltest.u-ga.fr/item/1250130390/