@misc{indiciae5ca1ac126d2e,
  title = {Method for constructing models with strong CP invariance.},
  author = {PH Frampton and TW Kephart},
  year = {1991},
  doi = {10.1103/physrevlett.66.1666},
  url = {https://pubmed.ncbi.nlm.nih.gov/10043276/},
  note = {Source identifier: 10043276}
}