@article{TRSPY_1987_180_a104,
     author = {S. V. Pereverzev},
     title = {Approximation numbers and the eigenvalue problem for integral operators},
     journal = {Informatics and Automation},
     pages = {175--176},
     publisher = {mathdoc},
     volume = {180},
     year = {1987},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/TRSPY_1987_180_a104/}
}