@article{IVM_1960_1_a19,
     author = {I. M. Petrov},
     title = {The order of approximation of functions of class $Z\alpha$ by certain polynomial operators},
     journal = {Izvesti\^a vys\v{s}ih u\v{c}ebnyh zavedenij. Matematika},
     pages = {188--193},
     publisher = {mathdoc},
     number = {1},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/IVM_1960_1_a19/}
}