@article{DE_1980_16_12_a0,
     author = {A. B. Budak},
     title = {Expansion in eigenfunctions of a fourth-order differential operator with discontinuous coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {2115--2126},
     year = {1980},
     volume = {16},
     number = {12},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1980_16_12_a0/}
}