%0 Journal Article
%A Zoltán Sasvári
%T New Proof of Naimark's Theorem on the Existence of Nonpositive Invariant Subspaces for Commuting Families of Unitary Operators in Pontryagin Spaces.
%J Monatshefte für Mathematik
%D 1990
%P 153-156
%V 109
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MOMA_1990__109_2_178466/
%F MOMA_1990__109_2_178466