@Misc{ 
  PinSpe16,
  author = { Pinamonti, Andrea and Speight, Gareth },
  title = { Porosity, Differentiability and Pansu's Theorem },
  journal = { Journal of Geometric Analysis },
  year = { 2016 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2961/ },
  note = { cvgmt preprint}
}