@article{DAN_1973_209_5_a7,
     author = {S. A. Smagin},
     title = {Fractional powers of a hypoelliptic operator in $\mathbf{R}^n$},
     journal = {Doklady Akademii Nauk},
     pages = {1033--1035},
     publisher = {mathdoc},
     volume = {209},
     number = {5},
     year = {1973},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1973_209_5_a7/}
}