@article{MZM_1972_12_1_a9,
     author = {A. M. Olevskii},
     title = {On operators generating conditional bases in a {Hilbert} space},
     journal = {Matemati\v{c}eskie zametki},
     pages = {73--84},
     publisher = {mathdoc},
     volume = {12},
     number = {1},
     year = {1972},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1972_12_1_a9/}
}