@misc{indiciae18f21e8ee299,
  title = {What is directionality?},
  author = {S Greenland and H Morgenstern},
  year = {1989},
  doi = {10.1016/0895-4356(89)90092-9},
  url = {https://pubmed.ncbi.nlm.nih.gov/2778461/},
  note = {Source identifier: 2778461}
}