@Article{ 
  Bar12,
  author = { Barilari, Davide },
  title = { Trace heat kernel asymptotics in 3D contact sub-Riemannian geometry },
  journal = { Journal of Mathematical Science },
  year = { 2013 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1824/ },
  note = { cvgmt preprint}
}