1. Begg CB, Mazumdar M (1994) Operating characteristics of a rank correlation test for publication bias. Biometrics 50:1088–1101
2. Chaparro LE, Furlan AD, Deshpande A et al (2013) Opioids compared to placebo or other treatments for chronic low-back pain. Cochrane Database Syst Rev 8:CD004959
3. Chou R, Carson S (2008) Drug class review on long-acting opioid analgesics: final report update 5 [Internet]. Oregon Health & Science University, Portland. http://www.ncbi.nlm.nih.gov/books/NBK10648/. Zugegriffen: 16. Dezember 2013
4. Chou R (2010) What we still don’t know about treating chronic noncancer pain with opioids. CMAJ 182:881–882
5. D’Agostino RB Sr, Massaro JM, Sullivan LM (2003) Non-inferiority trials: design concepts and issues—the encounters of academic consultants in statistics. Stat Med 22:169–186