@misc{indiciaefd73882b4fea,
  title = {Potentiometric surface maps of the Sparta Sand, northern Louisiana and southern Arkansas, 1900, 1965, 1975, and 1980},
  author = {G.N. Ryals},
  year = {1980},
  doi = {10.3133/ofr801180},
  url = {https://pubs.usgs.gov/publication/ofr801180},
  note = {Source identifier: ofr801180}
}