@Article{ 
  CasPac6,
  author = { Castorina, Daniele and Pacella, Filomena },
  title = { Symmetry of Solutions of a Semilinear Elliptic Problem in an Annulus },
  journal = {  Progress in Nonlinear Differential Equations and Their Applications },
  year = { 2006 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/3004/ },
  note = { cvgmt preprint}
}