@misc{indiciae0a7465cdf10e,
  title = {Non-thermal optical radiation from galaxies.},
  author = {Burbidge, G. R. and Demoulin, M.-H.},
  year = {1968},
  url = {https://ntrs.nasa.gov/citations/19680064730},
  note = {Source identifier: 19680064730}
}