@article{11342,
  author = {D. van Blerkom and David Hummer},
  title = {The ionization structure of planetary nebulae-VI. The Lyman continuum problem},
  year = {1967},
  journal = {Monthly Notices of the Royal Astronomical Society},
  volume = {137},
  chapter = {353},
  pages = {353-374},
  month = {00/1967},
  url = {http://articles.adsabs.harvard.edu/full/1967MNRAS.137..353V},
  doi = {10.1093/mnras/137.3.353},
  note = {JILA Pub. 300},
}