@article{TM_1975_138_a1,
     author = {V. V. Arestov},
     title = {Approximation of linear operators, and related extremal problems},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {29--42},
     publisher = {mathdoc},
     volume = {138},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1975_138_a1/}
}