Contouring a bivariate quadratic polynomial over a triangle

@article{Worsey1990ContouringAB,
  title={Contouring a bivariate quadratic polynomial over a triangle},
  author={Andrew J. Worsey and Gerald E. Farin},
  journal={Computer Aided Geometric Design},
  year={1990},
  volume={7},
  pages={337-351}
}