@misc{indiciae91db3ea33ebb,
  title = {Hydrology of the Mississippi River Valley alluvial aquifer, south- central United States — A preliminary assessment of the regional flow system},
  author = {D. J. Ackerman},
  year = {1989},
  doi = {10.3133/wri884028},
  url = {https://pubs.usgs.gov/publication/wri884028},
  note = {Source identifier: wri884028}
}