@misc{indiciae8f706a9c1a7e,
  title = {3D-DEF; a user's manual (a three-dimensional, boundary element modeling program)},
  author = {J.S. Gomberg and Michael Ellis},
  year = {1993},
  doi = {10.3133/ofr93547},
  url = {https://pubs.usgs.gov/publication/ofr93547},
  note = {Source identifier: ofr93547}
}