@misc{indiciae0d35e8eb33ed,
  title = {Distance to Cygnus X-1},
  author = {Margon, B. and Bowyer, S. and Kraft, R.},
  year = {1975},
  url = {https://ntrs.nasa.gov/citations/19770083392},
  note = {Source identifier: 19770083392}
}