@article{DAN_1992_323_6_a0,
     author = {V. D. Budaev},
     title = {The unconditional basis property of systems of root vector},
     journal = {Doklady Akademii Nauk},
     pages = {999--1003},
     publisher = {mathdoc},
     volume = {323},
     number = {6},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1992_323_6_a0/}
}