@misc{indiciaef7f1cd252516,
  title = {Shaded relief map of the Mare Boreum area of Mars},
  author = {Members of the Engineering Geology and Ground Water Branches, U.S. Geological Survey},
  year = {1976},
  doi = {10.3133/i969},
  url = {https://pubs.usgs.gov/publication/i969},
  note = {Source identifier: i969}
}