@article{DE_1972_8_12_a18,
     author = {V. P. Zakharov and Yu. V. Malyshev},
     title = {Application of generalized {Ljapunov} functions to the study of limit cycles on the plane},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2248--2250},
     publisher = {mathdoc},
     volume = {8},
     number = {12},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1972_8_12_a18/}
}