@Misc{ 
  d'ASqu16,
  author = { d'Avenia, Pietro and Squassina, Marco },
  title = { Ground states for fractional magnetic operators },
  journal = { ESAIM Control Optim. Calc. Var. },
  year = { 2016 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/2906/ },
  note = { cvgmt preprint}
}