@Article{ 
  gramar11,
  author = { Granlund, Seppo and Marola, Niko },
  title = { On a frequency function approach to the unique continuation principle  },
  journal = { Expo. Math. },
  year = { 2012 },
  doi = { 10.1016/j.exmath.2012.01.006 },
  volume = { 30 },
  number = { 2 },
  pages = { 154–167 },
  URL = { http://cvgmt.sns.it/paper/1089/ },
  note = { cvgmt preprint}
}