%0 Journal Article
%A I. I. Parovichenko
%T Certain special classes of topological spaces and $\delta s$-operations
%J Doklady Akademii Nauk
%D 1957
%P 866-868
%V 115
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_115_5_a3/
%G ru
%F DAN_1957_115_5_a3