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@article{DE_1971_7_3_a18, author = {B. S. Kalitin}, title = {The limit cycles of pendulum systems with impulse perturbation}, journal = {Differencialʹnye uravneni\^a}, pages = {540--542}, publisher = {mathdoc}, volume = {7}, number = {3}, year = {1971}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1971_7_3_a18/} }
B. S. Kalitin. The limit cycles of pendulum systems with impulse perturbation. Differencialʹnye uravneniâ, Tome 7 (1971) no. 3, pp. 540-542. http://geodesic.mathdoc.fr/item/DE_1971_7_3_a18/