@article{DE_2003_39_2_a0,
     author = {A. F. Andreev and A. P. Sadovskii and V. A. Tsikalyuk},
     title = {The {Center-Focus} {Problem} for a {System} with {Homogeneous} {Nonlinearities} in the {Case} of {Zero} {Eigenvalues} of the {Linear} {Part}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {147--153},
     publisher = {mathdoc},
     volume = {39},
     number = {2},
     year = {2003},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_2003_39_2_a0/}
}