%0 Journal Article %T On demand use of β2 agonists led to better asthma control than regular use in moderate to severe asthma %D 2001 %R 10.1136/ebm.6.1.15 %J Evidence Based Medicine %P 15-15 %V 6 %N 1 %U https://ebm.bmj.com/content/ebmed/6/1/15.full.pdf