@article{DE_1987_23_10_a9,
     author = {A. I. Vahabov},
     title = {Fourier series expansions in principal functions of an elliptic operator},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1736--1745},
     publisher = {mathdoc},
     volume = {23},
     number = {10},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1987_23_10_a9/}
}