TY - JOUR T1 - Should we avoid β-agonists for moderate and severe chronic obstructive pulmonary disease? JF - Canadian Family Physician JO - Can Fam Physician SP - 1290 LP - 1292 VL - 53 IS - 8 AU - Shawn D. Aaron Y1 - 2007/08/01 UR - http://www.cfp.ca/content/53/8/1290.2.abstract N2 - ER -