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@article{IVM_1986_11_a1, author = {M. I. Gil' and L. L. Shargorodskaya}, title = {On a~criterion for the existence of limit cycles}, journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika}, pages = {11--14}, publisher = {mathdoc}, number = {11}, year = {1986}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/IVM_1986_11_a1/} }
M. I. Gil'; L. L. Shargorodskaya. On a~criterion for the existence of limit cycles. Izvestiâ vysših učebnyh zavedenij. Matematika, no. 11 (1986), pp. 11-14. http://geodesic.mathdoc.fr/item/IVM_1986_11_a1/