@article{EJDE_2012__2012__a71,
     author = {Payne,  Victor F. and Tejumola,  Haroon Oladipo},
     title = {Existence and nonexistence of periodic solutions of \(n\)-vector differential equations of orders six and seven},
     journal = {Electronic journal of differential equations},
     year = {2012},
     volume = {2012},
     zbl = {1260.34077},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/EJDE_2012__2012__a71/}
}