@misc{indiciaeb154df3264f9,
  title = {Helical vs spiral.},
  author = {P M Silverman and K Corboy and R K Zeman},
  year = {1994},
  doi = {10.2214/ajr.162.5.8192801},
  url = {https://pubmed.ncbi.nlm.nih.gov/8192801/},
  note = {Source identifier: 8192801}
}