@article{AUPO_2002__41_1_a13,
     author = {Ukpera, Awar Simon},
     title = {Periodic solutions of certain third order differential systems with nonlinear dissipation},
     journal = {Acta Universitatis Palackianae Olomucensis. Facultas Rerum Naturalium. Mathematica},
     pages = {147--159},
     publisher = {mathdoc},
     volume = {41},
     number = {1},
     year = {2002},
     mrnumber = {1968227},
     zbl = {1040.34049},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/AUPO_2002__41_1_a13/}
}