@misc{indiciae81c2195e17cc,
  title = {Potentiometric surface of the upper Patapsco Aquifer in southern Maryland, September 1991},
  author = {Stephen E. Curtin and D. C. Andreasen and Frederick K. Mack},
  year = {1993},
  doi = {10.3133/ofr93654},
  url = {https://pubs.usgs.gov/publication/ofr93654},
  note = {Source identifier: ofr93654}
}