TY  - JOUR
AU  - E. F. Sachkova
TI  - Sub-Riemannian balls on the heisenberg groups: an invariant volume
JO  - Contemporary Mathematics. Fundamental Directions
PY  - 2011
SP  - 199
EP  - 203
VL  - 42
PB  - mathdoc
UR  - http://geodesic.mathdoc.fr/item/CMFD_2011_42_a18/
LA  - ru
ID  - CMFD_2011_42_a18
ER  -