@article{10644,
  author = {P. Kunasz and D. van Blerkom},
  title = {Mass loss from P Cygni. II - an equivalent two-level-atom approach},
  year = {1978},
  journal = {The Astrophysical Journal},
  volume = {224},
  pages = {193},
  month = {Jan-09-1978},
  issn = {0004-637X},
  url = {http://adsabs.harvard.edu/full/1978ApJ...224..193K},
  doi = {10.1086/156365},
}