@article{SM_1979_35_1_a4,
     author = {B. S. Kashin},
     title = {Remarks on estimating the {Lebesgue} functions of an orthonormal system},
     journal = {Sbornik. Mathematics},
     pages = {57--62},
     year = {1979},
     volume = {35},
     number = {1},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1979_35_1_a4/}
}