@misc{indiciaedc37f6a89f6b,
  title = {A modular three-dimensional finite-difference ground-water flow model},
  author = {Michael G. McDonald and Arlen W. Harbaugh},
  year = {1988},
  doi = {10.3133/twri06a1},
  url = {https://pubs.usgs.gov/publication/twri06A1},
  note = {Source identifier: twri06A1}
}