@article{BSMF_1962__90__449_0,
     author = {Kotake, Takeshi and Narasimhan, Mudumbai S.},
     title = {Regularity theorems for fractional powers of a linear elliptic operator},
     journal = {Bulletin de la Soci\'et\'e Math\'ematique de France},
     pages = {449--471},
     publisher = {Soci\'et\'e math\'ematique de France},
     volume = {90},
     year = {1962},
     doi = {10.24033/bsmf.1584},
     mrnumber = {26 #6819},
     zbl = {0104.32503},
     language = {en},
     url = {http://archive.numdam.org/articles/10.24033/bsmf.1584/}
}