@article{TM_1992_198_a0,
     author = {V. V. Arestov},
     title = {Best approximation ol unbounded operators invariant with respect to a~shift by the linear bounded operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {3--20},
     publisher = {mathdoc},
     volume = {198},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1992_198_a0/}
}