RT Journal Article SR Electronic T1 Tramadol: repeated prescriptions and repeated warnings JF BMJ Evidence-Based Medicine JO BMJ EBM FD BMJ Publishing Group Ltd SP bmjebm-2020-111661 DO 10.1136/bmjebm-2020-111661 A1 Anthony Richard Cox A1 Robin Ferner YR 2021 UL http://ebm.bmj.com/content/early/2021/03/11/bmjebm-2020-111661.abstract AB