@misc{indiciae4a568927d3a6,
  title = {Elevation-relief ratio, hypsometric integral, and geomorphic area-altitude analysis},
  author = {Richard J. Pike and Stephen E. Wilson},
  year = {1971},
  doi = {10.1130/0016-7606(1971)82[1079:erhiag]2.0.co;2},
  url = {https://pubs.usgs.gov/publication/70227441},
  note = {Source identifier: 70227441}
}