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@article{DE_1969_5_11_a13, author = {V. V. Amel'kin}, title = {The periodic solutions of a certain nonautonomous system}, journal = {Differencialʹnye uravneni\^a}, pages = {2085--2086}, publisher = {mathdoc}, volume = {5}, number = {11}, year = {1969}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1969_5_11_a13/} }
V. V. Amel'kin. The periodic solutions of a certain nonautonomous system. Differencialʹnye uravneniâ, Tome 5 (1969) no. 11, pp. 2085-2086. http://geodesic.mathdoc.fr/item/DE_1969_5_11_a13/