%0 Journal Article
%A M. G. Krein
%A G. K. Langer
%T On the theory of quadratic pencils of self-adjoint operators
%J Doklady Akademii Nauk
%D 1964
%P 1258-1261
%V 154
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/DAN_1964_154_6_a3/
%G ru
%F DAN_1964_154_6_a3