title: Fentanyl and alfentanil versus morphine for epidural analgesia.
mesh_terms: D015760:Alfentanil; D015360:Analgesia, Epidural; D005283:Fentanyl / Q000031:analogs & derivatives*; D006801:Humans; D009020:Morphine; D010149:Postoperative Pain / Q000628:therapy*
chemical_list: D015760:Alfentanil; D009020:Morphine; D005283:Fentanyl