Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DAN_1967_172_5_a2, author = {E. D. Garber}, title = {Periodic solutions of certain non-linear differential equations}, journal = {Doklady Akademii Nauk}, pages = {1003--1006}, publisher = {mathdoc}, volume = {172}, number = {5}, year = {1967}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DAN_1967_172_5_a2/} }
E. D. Garber. Periodic solutions of certain non-linear differential equations. Doklady Akademii Nauk, Tome 172 (1967) no. 5, pp. 1003-1006. http://geodesic.mathdoc.fr/item/DAN_1967_172_5_a2/