@article{DE_1970_6_8_a21,
     author = {O. A. Kononova},
     title = {The limit cycles of a certain system of nonlinear oscillations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1514--1515},
     publisher = {mathdoc},
     volume = {6},
     number = {8},
     year = {1970},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1970_6_8_a21/}
}