@Misc{ 
  ShaSpe18,
  author = { Shafrir, Itai and Spector, Daniel },
  title = { Best constants for two families of higher order critical Sobolev embeddings },
  journal = {  },
  year = { 2018 },
  pages = { 16 },
  URL = { http://cvgmt.sns.it/paper/3852/ },
  note = { cvgmt preprint}
}