@misc{indiciae9778c957498a,
  title = {Geologic map of the south central Rub Al Khali quadrangle, Kingdom of Saudi Arabia},
  author = {Leon F. Ramirez and E.L. Elberg and H.H. Helley},
  year = {1963},
  doi = {10.3133/i219a},
  url = {https://pubs.usgs.gov/publication/i219A},
  note = {Source identifier: i219A}
}