@article{TM_1985_172_a12,
     author = {B. S. Kashin},
     title = {On approximation properties of complete orthonormal systems},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {187--191},
     publisher = {mathdoc},
     volume = {172},
     year = {1985},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1985_172_a12/}
}