@misc{indiciae08e8e9751cd3,
  title = {Geologic map of the Bopolu Quadrangle, Liberia},
  author = {R.M. Wallace},
  year = {1977},
  doi = {10.3133/i772d},
  url = {https://pubs.usgs.gov/publication/i772D},
  note = {Source identifier: i772D}
}