Review
Opioids in the management of chronic non-cancer pain: an update of American Society of the Interventional Pain Physicians' (ASIPP) Guidelines.
Pain Physician. 2008 Mar 1;11(2 Suppl):S5-S62.
Review
Opioids in chronic non-cancer pain: systematic review of efficacy and safety.
Pain. 2004 Dec 1; 112 (3): 372380372-380.
Randomized Controlled Trial
Sustained-release oral morphine versus transdermal fentanyl and oral methadone in cancer pain management.
Eur J Pain. 2008 Nov 1;12(8):1040-6.