%0 Journal Article
%A E. F. Sachkova
%T Sub-Riemannian balls on the heisenberg groups: an invariant volume
%J Contemporary Mathematics. Fundamental Directions
%D 2011
%P 199-203
%V 42
%I mathdoc
%U http://geodesic.mathdoc.fr/item/CMFD_2011_42_a18/
%G ru
%F CMFD_2011_42_a18