%0 Journal Article
%A V. B. Lidskii
%T A theorem on the spectra of a perturbed differential operator
%J Doklady Akademii Nauk
%D 1957
%P 994-997
%V 112
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1957_112_6_a3/
%G ru
%F DAN_1957_112_6_a3