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@article{DE_1969_5_2_a18, author = {V. V. Amel'kin}, title = {The periodic solutions of a certain class of nonlinear systems}, journal = {Differencialʹnye uravneni\^a}, pages = {385--388}, publisher = {mathdoc}, volume = {5}, number = {2}, year = {1969}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1969_5_2_a18/} }
V. V. Amel'kin. The periodic solutions of a certain class of nonlinear systems. Differencialʹnye uravneniâ, Tome 5 (1969) no. 2, pp. 385-388. http://geodesic.mathdoc.fr/item/DE_1969_5_2_a18/