@Article{ 
  MetPal2,
  author = { Metafune, Giorgio and Pallara, Diego },
  title = { On the location of the essential spectrum of Schroedinger operators },
  journal = { Proc. Amer. Math. Soc.  },
  year = { 2002 },
  volume = { 130 },
  pages = { 1779-1786 },
  URL = { http://cvgmt.sns.it/paper/2428/ },
  note = { cvgmt preprint}
}