@Article{ 
  kocleomor,
  author = { Koch, Herbert and Leoni, Giovanni and Morini, Massimiliano },
  title = { On optimal regularity of free boundary problems and a conjecture of De Giorgi },
  journal = { Communications on Pure and Applied Mathematics },
  year = { 2005 },
  volume = { 58 },
  pages = { 1051-1076 },
  URL = { http://cvgmt.sns.it/paper/559/ },
  note = { cvgmt preprint}
}