@article{DE_1991_27_12_a14,
     author = {M. B. Muratbekov},
     title = {Separability of an operator of mixed type and the completeness of its root vectors},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2128--2137},
     publisher = {mathdoc},
     volume = {27},
     number = {12},
     year = {1991},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1991_27_12_a14/}
}