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@article{DE_1981_17_8_a21, author = {A. G. Sokolskii}, title = {On the stability of {Hamiltonian} systems in case of zero frequency}, journal = {Differencialʹnye uravneni\^a}, pages = {1509--1510}, publisher = {mathdoc}, volume = {17}, number = {8}, year = {1981}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1981_17_8_a21/} }
A. G. Sokolskii. On the stability of Hamiltonian systems in case of zero frequency. Differencialʹnye uravneniâ, Tome 17 (1981) no. 8, pp. 1509-1510. http://geodesic.mathdoc.fr/item/DE_1981_17_8_a21/