@Article{ 
  mar08,
  author = { Martinazzi, Luca },
  title = { Classification of solutions to the higher order Liouville's equation on
  R^{2m} },
  journal = { Math. Z. },
  year = { 2009 },
  volume = { 263 },
  pages = { 307-329 },
  URL = { http://cvgmt.sns.it/paper/226/ },
  note = { cvgmt preprint}
}