@article{05880331,
title = {Existence of periodic solutions for second order delay differential equations with impulses.},
journal = {Electronic Journal of Differential Equations (EJDE) [electronic only]},
volume = {2011},
year = {2011},
zbl = {1216.34078},
language = {en},
url = {http://dml.mathdoc.fr/item/05880331}
}
Pan, Lijun. Existence of periodic solutions for second order delay differential equations with impulses.. Electronic Journal of Differential Equations (EJDE) [electronic only], Tome 2011 (2011) . http://gdmltest.u-ga.fr/item/05880331/