@article{DE_2003_39_8_a6,
     author = {G. S. Rychkov},
     title = {A {Criterion} for the {Existence} of {Several} {Limit} {Cycles} of the {Abel} {Equation} of the {Second} {Kind}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1058--1061},
     publisher = {mathdoc},
     volume = {39},
     number = {8},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2003_39_8_a6/}
}