@misc{indiciaea206de4ec111,
  title = {Wick's theorem for charged spin systems.},
  author = {C Gros and MD Johnson},
  year = {1989},
  doi = {10.1103/physrevb.40.9423},
  url = {https://pubmed.ncbi.nlm.nih.gov/9991458/},
  note = {Source identifier: 9991458}
}