%0 Journal Article
%A I. D. Stupina
%T Properties of some $\delta s$-operations
%J Doklady Akademii Nauk
%D 1957
%P 188-190
%V 117
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_117_2_a6/
%G ru
%F DAN_1957_117_2_a6