@Article{ 
  drabar05,
  author = { Barletti, Luigi and Dragoni, Federica },
  title = { An inverse problem for two-frequency photon transport in a slab },
  journal = { Math. Models Methods Appl. Sci. },
  year = { 2005 },
  volume = { 28 },
  number = { 14 },
  pages = { 1695-1714 },
  URL = { http://cvgmt.sns.it/paper/508/ },
  note = { cvgmt preprint}
}