@article{7731,
  author = {P. Guilbert and Richard McCray and A. Fabian},
  title = {Why are broad emission lines seen in Seyfert galaxies and not in BL Lacertae objects},
  year = {1983},
  journal = {The Astrophysical Journal},
  volume = {266},
  pages = {466},
  month = {Jan-03-1983},
  issn = {0004-637X},
  url = {http://articles.adsabs.harvard.edu/full/1983ApJ...266..466G},
  doi = {10.1086/160794},
}