TY - JOUR T1 - Rebuttal: Should we avoid β-agonists for moderate and severe chronic obstructive pulmonary disease? JF - Canadian Family Physician JO - Can Fam Physician SP - 1429 LP - 1430 VL - 53 IS - 9 AU - Shelley R. Salpeter Y1 - 2007/09/01 UR - http://www.cfp.ca/content/53/9/1429.1.abstract N2 - ER -