@article{DAN_1968_178_6_a8,
     author = {P. L. Ul'yanov},
     title = {The imbedding of certain classes of functions of a single variable},
     journal = {Doklady Akademii Nauk},
     pages = {1259--1262},
     publisher = {mathdoc},
     volume = {178},
     number = {6},
     year = {1968},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1968_178_6_a8/}
}