@article{EJDE_2005__2005__a175,
     author = {Li,  Yongjin},
     title = {Existence of periodic solutions for second-order neutral differential equations},
     journal = {Electronic journal of differential equations},
     year = {2005},
     volume = {2005},
     zbl = {1075.34065},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2005__2005__a175/}
}