@article{EJDE_2012__2012__a37,
     author = {Yankson,  Ernest},
     title = {Positive periodic solutions for second-order neutral differential equations with functional delay},
     journal = {Electronic journal of differential equations},
     year = {2012},
     volume = {2012},
     zbl = {1243.34114},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2012__2012__a37/}
}