@Article{ 
  tilsci02,
  author = { Scianna, Giuseppe and Tilli, Paolo },
  title = { A variational  approach to the Hele--Shaw flow with injection },
  journal = { Communications in Partial Differential Equations },
  year = { 2005 },
  volume = { 30 },
  pages = { 1359-1378 },
  URL = { http://cvgmt.sns.it/paper/335/ },
  note = { cvgmt preprint}
}