@article{MZM_1986_40_2_a11,
     author = {V. V. Arestov},
     title = {Best approximation of unbounded by bounded operators, and allied problems},
     journal = {Matemati\v{c}eskie zametki},
     pages = {269--285},
     publisher = {mathdoc},
     volume = {40},
     number = {2},
     year = {1986},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1986_40_2_a11/}
}