@inproceedings{ijcai1981p113,
  title     = {On Shapes},
  author    = {Ballard, Dana H. and Sabbah, Daniel},
  booktitle = {Proceedings of the Seventh International Joint Conference on
               Artificial Intelligence, {IJCAI-81}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {Roger C. Schank},
  pages     = {607--611},
  year      = {1981},
  month     = {8},
  note      = {Vision: 3-d},
  url       = {https://ijcai.org/proceedings/1981/113},
}