@article{Matlak:2003,
  author  = "M. Matlak and J. Aksamit and B. Grabiec and W. Nolting",
  title   = "Hubbard Hamiltonian in the dimer representation Large-U case",
  journal = "Annalen der Physik",
  volume  = "Vol. 12",
  number  = "no 5",
  pages   = "304--319",
  year    = "2003",
}