@misc{indiciaeddd38129963c,
  title = {Ionization frequencies for solar cycle 21 - Revised},
  author = {Torr, M. R. and Torr, D. G.},
  year = {1985},
  url = {https://ntrs.nasa.gov/citations/19850058072},
  note = {Source identifier: 19850058072}
}