@article{HuebenerKruszynskaHartmannetal.2009,
  author    = {Robert H{\"u}bener and Caroline Kruszynska and Lorenz Hartmann and Wolfgang Duer and Frank Verstraete and Jens Eisert and Martin B. Plenio},
  title     = {Renormalization algorithm with graph enhancement},
  doi       = {10.1103/Physreva.79.022317},
  url       = {http://pra.aps.org/},
  year      = {2009},
}