@misc{indiciae99882e703659,
  title = {Geographic map of the Bopolu Quadrangle, Liberia},
  author = {Liberian Geological Survey},
  year = {1973},
  doi = {10.3133/i772a},
  url = {https://pubs.usgs.gov/publication/i772A},
  note = {Source identifier: i772A}
}