@article{IVM_2013_2_a2,
     author = {M. G. Grigoryan and S. A. Sargsyan},
     title = {Nonlinear approximation of functions from the class $L^r$ with respect to the {Vilenkin} system},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {30--39},
     publisher = {mathdoc},
     number = {2},
     year = {2013},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_2013_2_a2/}
}