@article{Wallis90,
  title = {Not all perfect extrinsic secret sharing schemes are ideal},
  author = {W. D. Wallis},
  year = {1990},
  url = {http://ajc.maths.uq.edu.au/pdf/2/ocr-ajc-v2-p237.pdf},
  researchr = {https://researchr.org/publication/Wallis90},
  cites = {0},
  citedby = {0},
  journal = {Australasian J. Combinatorics},
  volume = {2},
  pages = {237},
}