@article{Sandvik1999,
  author  = {A. W. Sandvik},
  title   = {Stochastic series expansion method with operator-loop update},
  journal = {Phys. Rev. B},
  volume  = {59},
  pages   = {R14157},
  year    = {1999},
  doi     = {10.1103/PhysRevB.59.R14157},
  eprint  = {cond-mat/9902226},
}