@misc{indiciae68f9769c8230,
  title = {Hadronic matrix elements and the pi +- pi 0 mass difference.},
  author = {WA Bardeen and J Bijnens and J Gérard},
  year = {1989},
  doi = {10.1103/physrevlett.62.1343},
  url = {https://pubmed.ncbi.nlm.nih.gov/10039649/},
  note = {Source identifier: 10039649}
}