TY  - JOUR
AU  - Robert Bieri
AU  - Ross Geoghegan
TI  - Sigma invariants of direct products of groups
JO  - Groups, geometry, and dynamics
PY  - 2010
SP  - 251
EP  - 261
VL  - 4
IS  - 2
UR  - http://geodesic.mathdoc.fr/articles/10.4171/ggd/82/
DO  - 10.4171/ggd/82
ID  - 10_4171_ggd_82
ER  -