@article{DE_1996_32_1_a5,
     author = {N. B. Kerimov},
     title = {On necessary and sufficient conditions for the basis property of systems of root functions of a differential operator},
     journal = {Differencialʹnye uravneni\^a},
     pages = {37--43},
     publisher = {mathdoc},
     volume = {32},
     number = {1},
     year = {1996},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1996_32_1_a5/}
}