@misc{1148366,
  author = {Daniel Raviv},
  title = {Flat surfaces::a visual invariant},
  year = {1992},
  month = {1992-01-01 05:01:00},
  publisher = {, National Institute of Standards and Technology, Gaithersburg, MD},
  doi = {https://doi.org/10.6028/NIST.IR.4794},
  language = {en},
}