@article{MZM_1975_17_5_a0,
     author = {N. B. Pogosyan},
     title = {On a~property of complete orthonormal systems},
     journal = {Matemati\v{c}eskie zametki},
     pages = {681--690},
     year = {1975},
     volume = {17},
     number = {5},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1975_17_5_a0/}
}