@article{DAN_1967_175_3_a2,
     author = {A. G. El'kin},
     title = {$A$-sets in complete metric spaces},
     journal = {Doklady Akademii Nauk},
     pages = {517--520},
     publisher = {mathdoc},
     volume = {175},
     number = {3},
     year = {1967},
     language = {ru},
     url = {http://geodesic.mathdoc.fr/item/DAN_1967_175_3_a2/}
}