@misc{indiciaec2366f8b81a7,
  title = {Isopotential surface maps.},
  author = {M Spach and R Barr and S Blumenschein and J Boineau},
  year = {1969},
  url = {https://pubmed.ncbi.nlm.nih.gov/4238861/},
  note = {Source identifier: 4238861}
}