@misc{indiciaebc440268d2ed,
  title = {The Difference Between the Potentiometric Surfaces of the Upper Patapsco Aquifer in Southern Maryland, September 1990 and September 2007},
  author = {Stephen E. Curtin and David C. Andreasen and Andrew W. Staley},
  year = {2009},
  doi = {10.3133/ofr20091085},
  url = {https://pubs.usgs.gov/publication/ofr20091085},
  note = {Source identifier: ofr20091085}
}