@misc{indiciae5580525c6cbb,
  title = {What is in a contour map? A region-based logical formalization of contour semantics},
  author = {E. Lynn Usery and Torsten Hahmann},
  year = {2015},
  doi = {10.1007/978-3-319-23374-1\_18},
  url = {https://pubs.usgs.gov/publication/70159738},
  note = {Source identifier: 70159738}
}