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@article{DE_1980_16_1_a12, author = {S. I. Pokhozhaev}, title = {Periodic solutions of some nonlinear systems of ordinary differential equations}, journal = {Differencialʹnye uravneni\^a}, pages = {109--116}, publisher = {mathdoc}, volume = {16}, number = {1}, year = {1980}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1980_16_1_a12/} }
S. I. Pokhozhaev. Periodic solutions of some nonlinear systems of ordinary differential equations. Differencialʹnye uravneniâ, Tome 16 (1980) no. 1, pp. 109-116. http://geodesic.mathdoc.fr/item/DE_1980_16_1_a12/