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@article{DE_1968_4_6_a5, author = {L. A. Cherkas}, title = {The stability of singular cycles}, journal = {Differencialʹnye uravneni\^a}, pages = {1012--1017}, publisher = {mathdoc}, volume = {4}, number = {6}, year = {1968}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1968_4_6_a5/} }
L. A. Cherkas. The stability of singular cycles. Differencialʹnye uravneniâ, Tome 4 (1968) no. 6, pp. 1012-1017. http://geodesic.mathdoc.fr/item/DE_1968_4_6_a5/