%0 Journal Article
%A V. M. Babich
%A B. M. Levitan
%T The focussing problem and the asymptotic behavior of the spectral function of the Laplace--Beltrami operator
%J Doklady Akademii Nauk
%D 1976
%P 1017-1020
%V 230
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1976_230_5_a0/
%G ru
%F DAN_1976_230_5_a0