@article{MZM_1993_53_1_a0,
     author = {R. K. Vasil'ev},
     title = {On the degree of the approximation of functions of several variables by linear positive operators of finite rank},
     journal = {Matemati\v{c}eskie zametki},
     pages = {3--15},
     publisher = {mathdoc},
     volume = {53},
     number = {1},
     year = {1993},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1993_53_1_a0/}
}