@article{IM2_1988_31_3_a1,
     author = {S. N. Kudryavtsev},
     title = {On~approximations of compact sets of functions by piecewise polynomial surfaces},
     journal = {Izvestiya. Mathematics },
     pages = {455--480},
     publisher = {mathdoc},
     volume = {31},
     number = {3},
     year = {1988},
     language = {en},
     url = {http://geodesic.mathdoc.fr/item/IM2_1988_31_3_a1/}
}