@article{9306,
  author = {Marek Sikora and Isaac Shlosman},
  title = {Ultra-high-energy photons from active galactic nuclei - Theory},
  year = {1989},
  journal = {The Astrophysical Journal},
  volume = {336},
  pages = {593},
  month = {Jan-01-1989},
  issn = {0004-637X},
  url = {http://articles.adsabs.harvard.edu/full/1989ApJ...336..593S},
  doi = {10.1086/167036},
}