@article{DE_2005_41_8_a10,
     author = {L. A. Cherkas and I. L. Shevtsov},
     title = {On the {Coppel} {Problem} for {Quadratic} {Systems} with a {Fine} {Focus}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1100--1104},
     publisher = {mathdoc},
     volume = {41},
     number = {8},
     year = {2005},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2005_41_8_a10/}
}