@misc{indiciae1bd6b8a1e9d2,
  title = {Semiannual variations in the neutral composition.},
  author = {Mayr, H. G. and Volland, H.},
  year = {1971},
  url = {https://ntrs.nasa.gov/citations/19720037561},
  note = {Source identifier: 19720037561}
}