Epidural opioid selection.

@article{Chrubasik1993EpiduralOS,
  title={Epidural opioid selection.},
  author={Joachim Chrubasik and Eike Martin and Sigrun A Chrubasik and Guy Friedrich},
  journal={Anesthesia and analgesia},
  year={1993},
  volume={76 3},
  pages={674-5}
}