Gavril W.G.W.PasternakGavril W.G.W., Ying-XianY.X.PanYing-XianY.X., Mu opioids and their receptors: evolution of a concept, „Pharmacological Reviews”, 65 (4), 2013, s. 1257–1317, DOI: 10.1124/pr.112.007138, PMID: 24076545, PMCID: PMC3799236.
Gavril W.G.W.PasternakGavril W.G.W., Ying-XianY.X.PanYing-XianY.X., Mu opioids and their receptors: evolution of a concept, „Pharmacological Reviews”, 65 (4), 2013, s. 1257–1317, DOI: 10.1124/pr.112.007138, PMID: 24076545, PMCID: PMC3799236.
Z.R.Z.R.ChenZ.R.Z.R. i inni, Disposition and metabolism of codeine after single and chronic doses in one poor and seven extensive metabolisers, „British Journal of Clinical Pharmacology”, 31 (4), 1991, s. 381–390, PMID: 2049245, PMCID: PMC1368322.
T.B.T.B.VreeT.B.T.B., R.T. vanR.T.DongenR.T. vanR.T., P.M.P.M.Koopman-KimenaiP.M.P.M., Codeine analgesia is due to codeine-6-glucuronide, not morphine, „International Journal of Clinical Practice”, 54 (6), 2000, s. 395–398, PMID: 11092114.