References?

  1. https://jamanetwork.com/journals/jama/fullarticle/188147?vis=539228583.14074560006240_
  2. https://www.sciencedirect.com/science/article/pii/S003194220086224X
  3. https://jamanetwork.com/journals/jama/fullarticle/1030240
  4. http://onlinelibrary.wiley.com/doi/10.1002/ptr.2323/abstract
  5. http://www.tandfonline.com/doi/abs/10.1271/bbb.80072
  6. https://link.springer.com/article/10.1023/A:1019911205672
  7. https://www.sciencedirect.com/science/article/pii/0306987788900813
  8. https://www.sciencedirect.com/science/article/pii/S0367326X03000364