@article{DE_1989_25_4_a22,
     author = {T. B. Kasumov},
     title = {Fractional powers of quasidifferential operators and theorems on the property of being a basis},
     journal = {Differencialʹnye uravneni\^a},
     pages = {729--731},
     year = {1989},
     volume = {25},
     number = {4},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1989_25_4_a22/}
}