@misc{indiciae661080d6e1fc,
  title = {Water levels and artesian pressures in the Chad Basin of northeastern Nigeria, 1963-68},
  author = {S.W. Carmalt and G. Chase Tibbitts},
  year = {1969},
  doi = {10.3133/ofr7261},
  url = {https://pubs.usgs.gov/publication/ofr7261},
  note = {Source identifier: ofr7261}
}