@misc{indiciae7e4eaefe84d1,
  title = {Electron concentration profiles during sunspot maximum and minimum.},
  author = {Lootens, H. T. and Prenatt, R. E.},
  year = {1968},
  url = {https://ntrs.nasa.gov/citations/19680038788},
  note = {Source identifier: 19680038788}
}