@article{11462,
  author = {E. Elst},
  title = {Photon escape from a semi-infinite atmosphere},
  year = {1968},
  journal = {Bulletin of the Astronomical Institutes of the Netherlands},
  volume = {20},
  chapter = {102},
  pages = {102-106},
  url = {http://adsabs.harvard.edu/full/1968BAN....20..102E},
  note = {JILA Pub. 311},
}