@article{DE_1999_35_12_a1,
     author = {V. M. Kurbanov},
     title = {Equiconvergence of biorthogonal expansions in root functions of differential {operators.~I}},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1597--1609},
     publisher = {mathdoc},
     volume = {35},
     number = {12},
     year = {1999},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1999_35_12_a1/}
}