@misc{indiciaeb30484807321,
  title = {Sand-sized heavy-mineral distributions in the Rio Cibuco system and adjacent rivers of north-central Puerto Rico},
  author = {Gretchen Luepke and L. J. Poppe},
  year = {1993},
  doi = {10.3133/ofr92703},
  url = {https://pubs.usgs.gov/publication/ofr92703},
  note = {Source identifier: ofr92703}
}