@article{EJDE_2002__2002__a216,
     author = {Jiang,  Daqing and Wei,  Junjie and Zhang,  Bo},
     title = {Positive periodic solutions of functional differential equations and population models},
     journal = {Electronic journal of differential equations},
     year = {2002},
     volume = {2002},
     zbl = {1010.34065},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2002__2002__a216/}
}