%0 Journal Article %A Fang, Hui %T Positive periodic solutions of $N$-species neutral delay systems %J Czechoslovak Mathematical Journal %D 2003 %P 561-570 %V 53 %N 3 %I mathdoc %U http://geodesic.mathdoc.fr/item/CMJ_2003__53_3_a5/ %G en %F CMJ_2003__53_3_a5