Voir la notice de l'article provenant de la source Math-Net.Ru
@article{DE_1985_21_11_a6, author = {V. N. Laptinskii}, title = {Fourier approximations of periodic solutions of nonlinear differential equations}, journal = {Differencialʹnye uravneni\^a}, pages = {1899--1904}, publisher = {mathdoc}, volume = {21}, number = {11}, year = {1985}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/DE_1985_21_11_a6/} }
V. N. Laptinskii. Fourier approximations of periodic solutions of nonlinear differential equations. Differencialʹnye uravneniâ, Tome 21 (1985) no. 11, pp. 1899-1904. http://geodesic.mathdoc.fr/item/DE_1985_21_11_a6/