@misc{indiciae3d645034e523,
  title = {QUANTUM VARIABLES AND THE ACTION PRINCIPLE.},
  author = {J Schwinger},
  year = {1961},
  doi = {10.1073/pnas.47.7.1075},
  url = {https://pubmed.ncbi.nlm.nih.gov/16590855/},
  note = {Source identifier: 16590855}
}