@Misc{ 
  vanBuc18,
  author = { Bucur, Dorin and van den Berg, Michiel },
  title = { Sign changing solutions of Poisson's equation },
  journal = {  },
  year = { 2018 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/4063/ },
  note = { cvgmt preprint}
}