@Misc{ 
  AmbFen13,
  author = { Ambrosio, Luigi and Feng, Jin },
  title = { On a class of first order Hamilton-Jacobi equations in metric spaces },
  journal = {  },
  year = { 2013 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2160/ },
  note = { cvgmt preprint}
}