@misc{indiciaeac0d5de58f3e,
  title = {Perturbation calculation around the two-dimensional Ising model.},
  author = {LF Ko},
  year = {1988},
  doi = {10.1103/physrevb.37.9889},
  url = {https://pubmed.ncbi.nlm.nih.gov/9944409/},
  note = {Source identifier: 9944409}
}