@article{IVM_1991_11_a6,
     author = {O. Kovachik},
     title = {Fourier--Haar double series},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {36--38},
     publisher = {mathdoc},
     number = {11},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1991_11_a6/}
}