@misc{indiciae530c47233716,
  title = {Exploration and evaluation of the Hajrah-Hamdah group of ancient gold mines, Kingdom of Saudi Arabia},
  author = {A. M. Helaby and Ronald G. Worl},
  year = {1981},
  doi = {10.3133/ofr81445},
  url = {https://pubs.usgs.gov/publication/ofr81445},
  note = {Source identifier: ofr81445}
}