@article{FAA_1972_6_3_a4,
     author = {Yu. S. Ilyashenko},
     title = {Algebraic nonsolvability and almost algebraic solvability of the centerfocus problem},
     journal = {Funkcionalʹnyj analiz i ego prilo\v{z}eni\^a},
     pages = {30--37},
     publisher = {mathdoc},
     volume = {6},
     number = {3},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/FAA_1972_6_3_a4/}
}