@misc{indiciaecfb2c0781208,
  title = {Geologic map of the Ptolemaeus Quadrangle of the moon},
  author = {K. A. Howard and Harold Masursky},
  year = {1968},
  doi = {10.3133/i566},
  url = {https://pubs.usgs.gov/publication/i566},
  note = {Source identifier: i566}
}