String graphs. I. The number of critical nonstring graphs is infinite

@article{Kratochvl1991StringGI,
  title={String graphs. I. The number of critical nonstring graphs is infinite},
  author={Jan Kratochv{\'i}l},
  journal={J. Comb. Theory, Ser. B},
  year={1991},
  volume={52},
  pages={53-66}
}