@article{IVM_1975_9_a9,
     author = {M. F. Timan and V. G. Ponomarenko},
     title = {The approximation of periodic functions of two variables by sums of {Marcinkiewicz} type},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {59--67},
     publisher = {mathdoc},
     number = {9},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1975_9_a9/}
}