@misc{indiciaecc5b3f56325a,
  title = {A simple contouring program for gridded data},
  author = {A.W. Harbaugh},
  year = {1990},
  doi = {10.3133/ofr90144},
  url = {https://pubs.usgs.gov/publication/ofr90144},
  note = {Source identifier: ofr90144}
}