@article{DAN_1960_131_2_a4,
     author = {I. A. Kipriyanov},
     title = {The fractional differentiation operator and powers of elliptic operators},
     journal = {Doklady Akademii Nauk},
     pages = {238--241},
     publisher = {mathdoc},
     volume = {131},
     number = {2},
     year = {1960},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1960_131_2_a4/}
}