@Misc{ 
  butkaw09,
  author = { Buttazzo, Giuseppe and Kawohl, Bernd },
  title = { Overdetermined boundary value problems for the $\infty$-Laplacian },
  journal = {  },
  year = { 2009 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/587/ },
  note = { cvgmt preprint}
}