RT Journal Article SR Electronic T1 Tiotropium improved lung function more than ipratropium in chronic obstructive pulmonary disease JF Evidence Based Medicine JO Evid Based Med FD BMJ Publishing Group Ltd SP 169 OP 169 DO 10.1136/ebm.5.6.169 VO 5 IS 6 YR 2000 UL http://ebm.bmj.com/content/5/6/169.abstract AB