@misc{indiciae73c548dd2b29,
  title = {Letter: The NSD formula.},
  author = {J S Orr},
  year = {1974},
  doi = {10.1259/0007-1285-47-563-824-a},
  url = {https://pubmed.ncbi.nlm.nih.gov/4434013/},
  note = {Source identifier: 4434013}
}