@article{DAN_1958_122_6_a1,
     author = {V. P. Glushko and S. G. Krein},
     title = {Fractional powers of differential operators and the imbedding theorems},
     journal = {Doklady Akademii Nauk},
     pages = {963--966},
     publisher = {mathdoc},
     volume = {122},
     number = {6},
     year = {1958},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1958_122_6_a1/}
}