@misc{indiciae7edd1a235c50,
  title = {Helicity, topology, and force-free fields.},
  author = {GE Marsh},
  year = {1993},
  doi = {10.1103/physreve.47.3607},
  url = {https://pubmed.ncbi.nlm.nih.gov/9960414/},
  note = {Source identifier: 9960414}
}