@misc{indiciae34cd1d04c724,
  title = {A photometric technique for determining planetary slopes from orbital photographs},
  author = {W.J. Bonner and R.A. Schmall},
  year = {1973},
  doi = {10.3133/pp812a},
  url = {https://pubs.usgs.gov/publication/pp812A},
  note = {Source identifier: pp812A}
}