RT Journal Article SR Electronic T1 Oversight of opioid advertising in Canada remains lax despite new federal guidance JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP E730 OP E731 DO 10.1503/cmaj.109-5612 VO 190 IS 23 A1 Webster, Paul YR 2018 UL http://www.cmaj.ca/content/190/23/E730.abstract