@inproceedings{ijcai1971p30,
  title     = {Pattern Linguistic Analysis Invariant for Plane Transformations},
  author    = {Simon, J. C. and Checroun, A.},
  booktitle = {Proceedings of the Second International Joint Conference on
               Artificial Intelligence, {IJCAI-71}},
  publisher = {International Joint Conferences on Artificial Intelligence},
  editor    = {D.C. Cooper},
  pages     = {308--316},
  year      = {1971},
  url       = {https://ijcai.org/proceedings/1971/30},
}