title: Historical aspects of opium.
mesh_terms: D000818:Animals; D002621:Chemistry; D049690:History, Ancient; D049691:History, Medieval; D049711:History, Modern 1601-; D006801:Humans; D009892:Opium / Q000266:history*; D011957:Receptors, Opioid / Q000502:physiology
chemical_list: D011957:Receptors, Opioid; D009892:Opium