@article{RM_1967_22_2_a14,
     author = {P. E. Sobolevskii},
     title = {On the $s$-numbers of integral operators},
     journal = {Trudy Matematicheskogo Instituta imeni V.A. Steklova},
     publisher = {mathdoc},
     volume = {22},
     number = {2},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/RM_1967_22_2_a14/}
}