@Article{ 
  KorKuuPal16a,
  author = { Korvenpaa, Janne and Kuusi, Tuomo and Palatucci, Giampiero },
  title = { Fractional superharmonic functions and the Perron method for nonlinear integro-differential equations },
  journal = { Math. Ann. },
  year = { 2017 },
  doi = { 10.1007/s00208-016-1495-x },
  volume = { 369 },
  number = { 3-4 },
  pages = { 1443-1489 },
  URL = { http://cvgmt.sns.it/paper/3027/ },
  note = { cvgmt preprint}
}