@article{SM_1999_190_7_a1,
     author = {M. I. Dyachenko},
     title = {Two-dimensional {Waterman} classes and $u$-convergence of {Fourier} series},
     journal = {Sbornik. Mathematics},
     pages = {955--972},
     year = {1999},
     volume = {190},
     number = {7},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/SM_1999_190_7_a1/}
}