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@article{DE_1972_8_10_a25, author = {G. E. Popov}, title = {A certain class of integrable equations with limit cycles}, journal = {Differencialʹnye uravneni\^a}, pages = {1898--1900}, publisher = {mathdoc}, volume = {8}, number = {10}, year = {1972}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1972_8_10_a25/} }
G. E. Popov. A certain class of integrable equations with limit cycles. Differencialʹnye uravneniâ, Tome 8 (1972) no. 10, pp. 1898-1900. http://geodesic.mathdoc.fr/item/DE_1972_8_10_a25/