%0 Journal Article
%A A. G. Kremlyov
%A Yu. G. Nikonorov
%T The signature of the Ricci curvature of left-invariant Riemannian metrics on four-dimensional Lie groups. The unimodular case
%J Matematičeskie trudy
%D 2008
%P 115-147
%V 11
%N 2
%I mathdoc
%U http://geodesic.mathdoc.fr/item/MT_2008_11_2_a3/
%G ru
%F MT_2008_11_2_a3