@Misc{ 
  CavRaj15,
  author = { Cavalletti, Fabio and Rajala, Tapio },
  title = { Tangent lines and Lipschitz differentiability spaces },
  journal = { Anal. Geom. Metr. Spaces },
  year = { 2015 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2640/ },
  note = { cvgmt preprint}
}