@misc{indiciae1dca075e3fb2,
  title = {Comet P/Halley's periodic brightness variations in 1910},
  author = {Schleicher, David G. and Bus, Schelte J.},
  year = {1991},
  url = {https://ntrs.nasa.gov/citations/19910039620},
  note = {Source identifier: 19910039620}
}