@misc{indiciae1a47ebc88d20,
  title = {Analytical results and sample locality map of soil samples from the Tanama-Helecho porphyry copper district, municipios of Utuado and Adjuntas, Puerto Rico},
  author = {R. E. Learned and H. A. Pierce and Ileana Perez},
  year = {1992},
  doi = {10.3133/ofr93179},
  url = {https://pubs.usgs.gov/publication/ofr93179},
  note = {Source identifier: ofr93179}
}