@article{DAN_1989_306_1_a9,
     author = {Kh. P. Rustamov},
     title = {On differential-smoothness properties of functions in the space},
     journal = {Doklady Akademii Nauk},
     pages = {46--51},
     publisher = {mathdoc},
     volume = {306},
     number = {1},
     year = {1989},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1989_306_1_a9/}
}