@article{SM_1969_9_1_a3,
     author = {S. V. Bochkarev},
     title = {On~the coefficients of {Fourier} series with respect to the {Haar} system},
     journal = {Sbornik. Mathematics},
     pages = {93--109},
     publisher = {mathdoc},
     volume = {9},
     number = {1},
     year = {1969},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1969_9_1_a3/}
}