@misc{indiciaefcaa89b17e5b,
  title = {Maps showing gravity and aeromagnetic anomalies in the Butte 1° x 2° quadrangle, Montana},
  author = {W. F. Hanna and J. H. Hassemer and J. E. Elliott and C. A. Wallace and S. L. Snyder},
  year = {1994},
  doi = {10.3133/i2050i},
  url = {https://pubs.usgs.gov/publication/i2050I},
  note = {Source identifier: i2050I}
}