@article{TRSPY_1987_180_a28,
     author = {Yu. A. Brudnyi and P. A. Shvartsman},
     title = {Extension of functions with preservation of smoothness},
     journal = {Informatics and Automation},
     pages = {60--61},
     publisher = {mathdoc},
     volume = {180},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1987_180_a28/}
}