@article{DAN_1965_165_5_a2,
     author = {P. P. Zabreiko and M. A. Krasnosel'skii and E. I. Pustyl'nik},
     title = {On fractional powers of elliptic operators},
     journal = {Doklady Akademii Nauk},
     pages = {990--993},
     publisher = {mathdoc},
     volume = {165},
     number = {5},
     year = {1965},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1965_165_5_a2/}
}