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@article{DE_1985_21_9_a5, author = {A. P. Sadovskii}, title = {Formal orbital normal forms of two-dimensional systems with nonzero linear part}, journal = {Differencialʹnye uravneni\^a}, pages = {1509--1516}, publisher = {mathdoc}, volume = {21}, number = {9}, year = {1985}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1985_21_9_a5/} }
A. P. Sadovskii. Formal orbital normal forms of two-dimensional systems with nonzero linear part. Differencialʹnye uravneniâ, Tome 21 (1985) no. 9, pp. 1509-1516. http://geodesic.mathdoc.fr/item/DE_1985_21_9_a5/