Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MZM_2001_70_4_a14, author = {B. S. Kashin}, title = {Lower {Bounds} for $n${-Term} {Approximations}}, journal = {Matemati\v{c}eskie zametki}, pages = {636--638}, publisher = {mathdoc}, volume = {70}, number = {4}, year = {2001}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_2001_70_4_a14/} }
B. S. Kashin. Lower Bounds for $n$-Term Approximations. Matematičeskie zametki, Tome 70 (2001) no. 4, pp. 636-638. http://geodesic.mathdoc.fr/item/MZM_2001_70_4_a14/