@misc{indiciaeb8fad4819071,
  title = {Fluorspar resources of Africa},
  author = {Ralph Erskine Van Alstine and Paul G. Schruben},
  year = {1980},
  doi = {10.3133/b1487},
  url = {https://pubs.usgs.gov/publication/b1487},
  note = {Source identifier: b1487}
}