@article{EJDE_2005__2005__a31,
     author = {Alwash,  Mohamad A.M.},
     title = {Periodic solutions of polynomial non-autonomous differential equations},
     journal = {Electronic journal of differential equations},
     year = {2005},
     volume = {2005},
     zbl = {1075.34514},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2005__2005__a31/}
}