@article{DAN_1975_223_6_a4,
     author = {O. I. Kuznetsova},
     title = {On some properties of polynomial operators of triangular form in a space of continuous periodic functions of two variables},
     journal = {Doklady Akademii Nauk},
     pages = {1304--1306},
     publisher = {mathdoc},
     volume = {223},
     number = {6},
     year = {1975},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1975_223_6_a4/}
}