Cooper, Christopher; Anzueto, Antonio; Decramer, Marc; Celli, ; Tashkin, Donald; Leimer, ; Kesten, . (2011). Tiotropium reduces risk of exacerbations irrespective of previous use of inhaled anticholinergics in placebo-controlled clinical trials. International Journal of Chronic Obstructive Pulmonary Disease, (), 269–.
doi:10.2147/COPD.S17864
