RT Journal Article SR Electronic T1 Long-acting β2-agonists in asthma: safety concerns JF Canadian Medical Association Journal JO CMAJ FD Canadian Medical Association SP 1030 OP 1031 DO 10.1503/cmaj.051224 VO 173 IS 9 A1 Wooltorton, Eric YR 2005 UL http://www.cmaj.ca/content/173/9/1030.abstract