%0 Journal Article
%A E. G. Sitnikova
%T A~three spheres theorem for an elliptic equation of high order
%J Sbornik. Mathematics
%D 1970
%P 189-195
%V 11
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/SM_1970_11_2_a3/
%G en
%F SM_1970_11_2_a3