@misc{indiciae11375b87ad16,
  title = {Geologic map of the western Rub Al Khali quadrangle, Kingdom of Saudi Arabia},
  author = {Richard A. Bramkamp and Ruel D. Gierhart and Lloyd D. Owens},
  year = {1963},
  doi = {10.3133/i218a},
  url = {https://pubs.usgs.gov/publication/i218A},
  note = {Source identifier: i218A}
}