@article{DE_1967_3_8_a2,
     author = {I. M. Belen'kii},
     title = {Sufficient conditions for the absence of periodic trajectories of autonomous systems in the case of multiply connected regions},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1248--1252},
     publisher = {mathdoc},
     volume = {3},
     number = {8},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1967_3_8_a2/}
}