@misc{indiciaea60d1960bb87,
  title = {Bouguer gravity maps, rock property data, and principal facts for gravity data compiled for the island of Puerto Rico and vicinity},
  author = {N. E. Kitchen and V.E. Langenheim and W. L. Rambo and Andrew Griscom},
  year = {1991},
  doi = {10.3133/ofr91633a},
  url = {https://pubs.usgs.gov/publication/ofr91633A},
  note = {Source identifier: ofr91633A}
}