%0 Journal Article
%A V. Ya. Ivrii
%T The energy integral for nonstrictly hyperbolic operators
%J Trudy Matematicheskogo Instituta imeni V.A. Steklova
%D 1975
%V 30
%N 6
%I mathdoc
%U http://geodesic.mathdoc.fr/item/RM_1975_30_6_a12/
%G ru
%F RM_1975_30_6_a12