@article{Dekeyser:1994,
  author  = "R. Dekeyser and A. Drzewiński and J. Van Leeuwen",
  title   = "A new renormalization approach to the ground state of the anisotropic XY model",
  journal = "Acta Physica Slovaca",
  volume  = "Vol. 44",
  number  = "no 4/5",
  pages   = "357--364",
  year    = "1994",
}