@article{7468,
  author = {David Hummer and G. Rybicki},
  title = {Second-order escape probability approximations in radiative transfer},
  year = {1982},
  journal = {The Astrophysical Journal},
  volume = {263},
  pages = {925},
  month = {Jan-12-1982},
  issn = {0004-637X},
  url = {http://articles.adsabs.harvard.edu/full/1982ApJ...263..925H},
  doi = {10.1086/160560},
}