@article{TM_1972_117_a4,
     author = {V. I. Burenkov},
     title = {The approximation of functions in the space $C^{r}(\Omega )$ by functions of compact support, for an arbitrary open set~$\Omega $},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     pages = {62--74},
     year = {1972},
     volume = {117},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TM_1972_117_a4/}
}