@article{CramerEisertPlenioetal.2006,
  author    = {Marcus Cramer and Jens Eisert and Martin B. Plenio and Julian Dreißig},
  title     = {Entanglement-area law for general bosonic harmonic lattice systems},
  doi       = {10.1103/Physreva.73.012309},
  url       = {http://pra.aps.org/},
  year      = {2006},
}