@article{DAN_1966_166_6_a9,
     author = {P. E. Sobolevskii},
     title = {On fractional powers of weakly positive operators},
     journal = {Doklady Akademii Nauk},
     pages = {1296--1299},
     publisher = {mathdoc},
     volume = {166},
     number = {6},
     year = {1966},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1966_166_6_a9/}
}