@Article{ 
  cridel,
  author = { Crippa, Gianluca and De Lellis, Camillo },
  title = { Regularity and compactness for the DiPerna--Lions flow },
  journal = { Hyperbolic Problems: Theory, Numerics, Applications },
  year = { 2008 },
  pages = { 423-430 },
  URL = { http://cvgmt.sns.it/paper/1226/ },
  note = { cvgmt preprint}
}