@misc{indiciaeca42b6cb6588,
  title = {Multiple opioid systems and pain.},
  author = {Mark J Millan},
  year = {1986},
  doi = {10.1016/0304-3959(86)90158-2},
  url = {https://pubmed.ncbi.nlm.nih.gov/3027643/},
  note = {Source identifier: 3027643}
}