%0 Journal Article
%A Cheng,  Sui Sun
%A Zhang,  Guang
%T Existence of positive periodic solutions for non-autonomous functional differential equations
%J Electronic journal of differential equations
%D 2001
%V 2001
%U http://geodesic.mathdoc.fr/item/EJDE_2001__2001__a3/
%G en
%F EJDE_2001__2001__a3