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@article{MS_1958__86_2_a9, author = {{\CYRA}.{\CYRV}. {\CYRG}{\cyrl}{\cyra}{\cyrd}{\cyrk}{\cyri}{\cyrishrt}}, title = {{\CYRR}{\cyra}{\cyrz}{\cyrr}{\cyre}{\cyrzh}{\cyre}{\cyrn}{\cyrn}{\cyrery}{\cyre} {\cyrk}{\cyrl}{\cyra}{\cyrs}{\cyrs}{\cyrery} {\cyrm}{\cyrn}{\cyro}{\cyrzh}{\cyre}{\cyrs}{\cyrt}{\cyrv}, {\cyrd}{\cyro}{\cyrp}{\cyru}{\cyrs}{\cyrk}{\cyra}{\cyryu}{\cyrshch}{\cyri}{\cyre} {\cyrp}{\cyro}{\cyrk}{\cyrr}{\cyrery}{\cyrt}{\cyri}{\cyrya} $F_\ensuremath{\sigma}$}, journal = {Matemati\v{c}eskij sbornik}, pages = {287--295}, publisher = {mathdoc}, volume = {86}, number = {2}, year = {1958}, zbl = {0080.03802}, language = {ru}, url = {http://geodesic.mathdoc.fr/item/MS_1958__86_2_a9/} }
А.В. Гладкий. Разреженные классы множеств, допускающие покрытия $F_σ$. Matematičeskij sbornik, Tome 86 (1958) no. 2, pp. 287-295. http://geodesic.mathdoc.fr/item/MS_1958__86_2_a9/