@Article{ 
  NguNgu16,
  author = { Nguyen, Hoai-Minh and Nguyen, Quoc-Hung },
  title = { Discreteness of interior transmission eigenvalues revisited },
  journal = { Calculus of Variations and Partial Differential Equations },
  year = { 2017 },
  doi = { https://link.springer.com/article/10.1007/s00526-017-1143-7 },
  pages = {  },
  URL = { http://cvgmt.sns.it/paper/3446/ },
  note = { cvgmt preprint}
}