%0 Journal Article
%A Pan,  Lijun
%T Existence of periodic solutions for second order delay differential equations with impulses
%J Electronic journal of differential equations
%D 2011
%V 2011
%U http://geodesic.mathdoc.fr/item/EJDE_2011__2011__a57/
%G en
%F EJDE_2011__2011__a57