@Misc{ 
  CatMas16,
  author = { Catino, Giovanni and Mastrolia, Paolo },
  title = { Bochner type formulas for the Weyl tensor on four dimensional Einstein
  manifolds },
  journal = {  },
  year = { 2016 },
  pages = {  },
  URL = { https://gecogedi.dimai.unifi.it/paper/525/ },
  note = { cvgmt preprint}
}