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@article{MZM_1979_26_3_a6, author = {A. S. Kats}, title = {Best approximation to an element in {a~Banach} space by a system of seminorm}, journal = {Matemati\v{c}eskie zametki}, pages = {377--388}, publisher = {mathdoc}, volume = {26}, number = {3}, year = {1979}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MZM_1979_26_3_a6/} }
A. S. Kats. Best approximation to an element in a~Banach space by a system of seminorm. Matematičeskie zametki, Tome 26 (1979) no. 3, pp. 377-388. http://geodesic.mathdoc.fr/item/MZM_1979_26_3_a6/