@article{DAN_1991_321_5_a0,
     author = {V. D. Budaev},
     title = {A necessary condition for the {Riesz} basis property of systems of},
     journal = {Doklady Akademii Nauk},
     pages = {873--875},
     publisher = {mathdoc},
     volume = {321},
     number = {5},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1991_321_5_a0/}
}