@misc{indiciaea45bc1e17817,
  title = {Solar activity prediction},
  author = {Slutz, R. J. and Gray, T. B. and West, M. L. and Stewart, F. G. and Leftin, M.},
  year = {1971},
  url = {https://ntrs.nasa.gov/citations/19720005158},
  note = {Source identifier: 19720005158}
}