human opiorphin is a potent yet non-addictive analgesic without drug tolerance effects. J. Physiol. Pharmacol. August 2010, 61 (4): 483–90. PMID 20814077
ISBN 978-0-7509-4583-7 Thompson, Irene, The A to Z of Punishment and Torture: From Amputations to Zero Tolerance, Book Guild Publishing, 2008, ISBN 978-1-84624-203-8