@article{DE_1992_28_6_a3,
     author = {A. B. Budak and V. N. Denisov},
     title = {Estimation of the closeness of partial sums of expansions in eigenfunctions of a {Sturm--Liouville} operator with discontinuous coefficients},
     journal = {Differencialʹnye uravneni\^a},
     pages = {943--956},
     publisher = {mathdoc},
     volume = {28},
     number = {6},
     year = {1992},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1992_28_6_a3/}
}