TY  - JOUR
AU  - A. G. Kremlyov
AU  - Yu. G. Nikonorov
TI  - The signature of the Ricci curvature of left-invariant Riemannian metrics on four-dimensional Lie groups. The nonunimodular case
JO  - Matematičeskie trudy
PY  - 2009
SP  - 40
EP  - 116
VL  - 12
IS  - 1
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/MT_2009_12_1_a2/
LA  - ru
ID  - MT_2009_12_1_a2
ER  -