@article{DE_1978_14_7_a2,
     author = {M. V. Dolov},
     title = {Darboux integrals in the case of a focus},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1173--1178},
     publisher = {mathdoc},
     volume = {14},
     number = {7},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_7_a2/}
}