@Article{ 
  fragazkaw,
  author = { Fragalà, Ilaria and Gazzola, Filippo and Kawohl, Bernd },
  title = { Overdetermined problems with possibly degenerate ellipticity, a geometric approach },
  journal = { Math. Zeitschrift },
  year = { 2006 },
  volume = { 254 },
  pages = { 117-132 },
  URL = { http://cvgmt.sns.it/paper/873/ },
  note = { cvgmt preprint}
}