@article{DE_1996_32_1_a9,
     author = {I. S. Lomov},
     title = {On the rate of convergence of biorthogonal series connected with second-order differential operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {71--82},
     publisher = {mathdoc},
     volume = {32},
     number = {1},
     year = {1996},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1996_32_1_a9/}
}