%0 Journal Article %A I. D. Evzerov %A P. E. Sobolevskii %T Fractional powers of ordinary differential operators %J Differencialʹnye uravneniâ %D 1973 %P 228-240 %V 9 %N 2 %I mathdoc %U http://geodesic.mathdoc.fr/item/DE_1973_9_2_a3/ %G ru %F DE_1973_9_2_a3