@article{00753682,
title = {Existence of periodic solutions for nonlinear Li\'enard systems.},
journal = {International Journal of Mathematics and Mathematical Sciences},
volume = {18},
year = {1995},
pages = {265-272},
doi = {10.1155/S0161171295000329},
zbl = {0821.34018},
language = {en},
url = {http://dml.mathdoc.fr/item/00753682}
}
Kim, Wan Se. Existence of periodic solutions for nonlinear Liénard systems.. International Journal of Mathematics and Mathematical Sciences, Tome 18 (1995) pp. 265-272. doi : 10.1155/S0161171295000329. http://gdmltest.u-ga.fr/item/00753682/