Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MZM_1990_48_4_a16, author = {A. A. Yudin and V. A. Yudin}, title = {On {Jackson's} theorems in~$L_2$}, journal = {Matemati\v{c}eskie zametki}, pages = {152--157}, publisher = {mathdoc}, volume = {48}, number = {4}, year = {1990}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1990_48_4_a16/} }
A. A. Yudin; V. A. Yudin. On Jackson's theorems in~$L_2$. Matematičeskie zametki, Tome 48 (1990) no. 4, pp. 152-157. http://geodesic.mathdoc.fr/item/MZM_1990_48_4_a16/