@article{Drzewiński:1991,
  author  = "A. Drzewiński and J. Sznajd and J. Zittartz",
  title   = "Renormalization group approach to three-state spin models in two dimensions",
  journal = "Zeitschrift für Physik B - Condensed Matter",
  volume  = "Vol. 84",
  pages   = "125--129",
  year    = "1991",
}