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@article{DE_1994_30_10_a20, author = {V. A. Baikov}, title = {Approximate symmetries of an equation of van der {Pol} type}, journal = {Differencialʹnye uravneni\^a}, pages = {1820--1822}, publisher = {mathdoc}, volume = {30}, number = {10}, year = {1994}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1994_30_10_a20/} }
V. A. Baikov. Approximate symmetries of an equation of van der Pol type. Differencialʹnye uravneniâ, Tome 30 (1994) no. 10, pp. 1820-1822. http://geodesic.mathdoc.fr/item/DE_1994_30_10_a20/