"Reliable Two-Dimensional Graphing Methods for Mathematical Formulae with Two Free Variables" http://www.dgp.toronto.edu/people/mooncake/papers/SIGGRAPH2001_Tupper.pdf* Weisstein, Eric W. "Tupper's Self-Referential Formula.
«Reliable Two-Dimensional Graphing Methods for Mathematical Formulae with Two Free Variables» http://www.dgp.toronto.edu/people/mooncake/papers/SIGGRAPH2001_Tupper.pdf* Weisstein, Eric W. «Tupper's Self-Referential Formula.» From MathWorld--A Wolfram Web Resource.