@article{MZM_1973_13_5_a3,
     author = {A. I. Stepanets},
     title = {The approximation of continuous periodic functions of two variables by {Faward} sums},
     journal = {Matemati\v{c}eskie zametki},
     pages = {655--666},
     publisher = {mathdoc},
     volume = {13},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/MZM_1973_13_5_a3/}
}