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@article{DE_1971_7_11_a3, author = {E. D. Zhitelzeif}, title = {The limit cycles of a certain autonomous system}, journal = {Differencialʹnye uravneni\^a}, pages = {1967--1973}, publisher = {mathdoc}, volume = {7}, number = {11}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1971_7_11_a3/} }
E. D. Zhitelzeif. The limit cycles of a certain autonomous system. Differencialʹnye uravneniâ, Tome 7 (1971) no. 11, pp. 1967-1973. http://geodesic.mathdoc.fr/item/DE_1971_7_11_a3/