%0 Journal Article
%A M. G. Gasymov
%A B. M. Levitan
%T On the sum of the differences of the eigenvalues of two singular Sturm--Liouville operators
%J Doklady Akademii Nauk
%D 1963
%P 1014-1017
%V 151
%N 5
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1963_151_5_a4/
%G ru
%F DAN_1963_151_5_a4