Voir la notice de l'article provenant de la source Math-Net.Ru
@article{MZM_1989_46_1_a8, author = {O. A. Timoshin}, title = {Best approximation of partial differential operators}, journal = {Matemati\v{c}eskie zametki}, pages = {78--87}, publisher = {mathdoc}, volume = {46}, number = {1}, year = {1989}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1989_46_1_a8/} }
O. A. Timoshin. Best approximation of partial differential operators. Matematičeskie zametki, Tome 46 (1989) no. 1, pp. 78-87. http://geodesic.mathdoc.fr/item/MZM_1989_46_1_a8/