@misc{indiciae03cdb162eda1,
  title = {D region electron density variations during winter 1972-73},
  author = {Bowhill, S. A. and Denny, B. W.},
  year = {1974},
  url = {https://ntrs.nasa.gov/citations/19740056872},
  note = {Source identifier: 19740056872}
}