@Misc{ 
  Cat12,
  author = { Catino, Giovanni },
  title = { Critical metrics of the $L^2$-norm of the scalar curvature },
  journal = { Proc. Amer. Math. Soc. },
  year = { 2013 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/1822/ },
  note = { cvgmt preprint}
}