%0 Journal Article
%A I. I. Parovichenko
%T On the commutativity of $\delta s$-operations
%J Doklady Akademii Nauk
%D 1975
%P 284-287
%V 222
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1975_222_2_a5/
%G ru
%F DAN_1975_222_2_a5