@article{DE_1993_29_2_a4,
     author = {A. P. Sadovskii},
     title = {Limit cycles of a cubic system of nonlinear oscillations},
     journal = {Differencialʹnye uravneni\^a},
     pages = {226--231},
     publisher = {mathdoc},
     volume = {29},
     number = {2},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1993_29_2_a4/}
}