@article{Alet2005pre,
  author  = {F. Alet and S. Wessel and M. Troyer},
  title   = {Generalized directed loop method for quantum {M}onte {C}arlo simulations},
  journal = {Phys. Rev. E},
  volume  = {71},
  pages   = {036706},
  year    = {2005},
  doi     = {10.1103/PhysRevE.71.036706},
  eprint  = {cond-mat/0308495},
}