@article{IM2_1973_7_3_a8,
     author = {S. V. Bochkarev},
     title = {On a~problem of {Zygmund}},
     journal = {Izvestiya. Mathematics},
     pages = {629--637},
     year = {1973},
     volume = {7},
     number = {3},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1973_7_3_a8/}
}