@article{UZMU_1951_148_148_a7,
     author = {N. K. Bari},
     title = {Biorthogonal systems and bases in {Hilbert} space},
     journal = {Uchenye Zapiski Moskovskogo Gosudarstvennogo Universiteta},
     pages = {69--107},
     publisher = {mathdoc},
     volume = {148},
     number = {148},
     year = {1951},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/UZMU_1951_148_148_a7/}
}