D. Barilari, T. Bossio:
Steiner and tube formulae in 3D contact sub-Riemannian geometry
Communication in Contemporary Mathematics (Accepted Paper) 2023

T. Bossio, L. Rizzi, T. Rossi:
Tubes in sub-Riemannian geometry and a Weyl's invariance result for
  curves in the Heisenberg groups
(preprint) 2024