@article{DE_1978_14_8_a12,
     author = {B. D. Kotlyar},
     title = {Singular numbers of integral operators},
     journal = {Differencialʹnye uravneni\^a},
     pages = {1473--1477},
     publisher = {mathdoc},
     volume = {14},
     number = {8},
     year = {1978},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DE_1978_14_8_a12/}
}