@misc{indiciaea8fa64aca779,
  title = {A systematic search for long-term variability in a large sample of X-ray sources},
  author = {Maccacaro, Tommaso and Garilli, Bianca and Mereghetti, Sandro},
  year = {1987},
  url = {https://ntrs.nasa.gov/citations/19870056867},
  note = {Source identifier: 19870056867}
}