@misc{indiciae315fc6fae915,
  title = {A simplified method for determining the angle between two spatial vectors.},
  author = {R A HELM and N O FOWLER},
  year = {1953},
  doi = {10.1016/0002-8703(53)90131-8},
  url = {https://pubmed.ncbi.nlm.nih.gov/13050595/},
  note = {Source identifier: 13050595}
}