@article{DE_1975_11_11_a2,
     author = {M. V. Dolov},
     title = {Limit cycles and algebraic integrals in the case of a center},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1935--1941},
     publisher = {mathdoc},
     volume = {11},
     number = {11},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1975_11_11_a2/}
}