@misc{indiciaec6ef10cbdca4,
  title = {Bouguer gravity map of the northern Mississippi Embayment, parts of Missouri, Arkansas, Tennessee, Kentucky, and Illinois},
  author = {T.G. Hildenbrand and C. P. Ervin and John Hendricks and Gordon R. Keller and L. D. McGinnis and R. G. Stearns},
  year = {1977},
  doi = {10.3133/ofr77228},
  url = {https://pubs.usgs.gov/publication/ofr77228},
  note = {Source identifier: ofr77228}
}