@article{10_4064_ap103_3_1,
     author = {Fei Long and Bingwen Liu},
     title = {Existence and uniqueness of positive periodic solutions
 of delayed {Nicholson's} blowflies models},
     journal = {Annales Polonici Mathematici},
     pages = {217--228},
     publisher = {mathdoc},
     volume = {103},
     number = {3},
     year = {2012},
     doi = {10.4064/ap103-3-1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/articles/10.4064/ap103-3-1/}
}