@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},
     year = {1979},
     volume = {26},
     number = {3},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1979_26_3_a6/}
}