@article{10_4153_CJM_1987_027_6,
     author = {Nkashama, M. N.},
     title = {Existence, {Unicite} et {Multiplicite} de {Solutions} {Periodiques} {D'Equations} {Differentielles} de {Duffing} {Non-Lineaires} {Avec} {Dissipation}},
     journal = {Canadian journal of mathematics},
     pages = {583--602},
     year = {1987},
     volume = {39},
     number = {3},
     doi = {10.4153/CJM-1987-027-6},
     url = {http://geodesic.mathdoc.fr/articles/10.4153/CJM-1987-027-6/}
}