Plethysmography and impulse oscillometry assessment of tiotropium and ipratropium bromide; a randomized, double-blind, placebo-controlled, cross-over study in healthy subjects. - Singh, D.; Tal-Singer, R.; Faiferman, I.; Lasenby, S.; Henderson, A.; Wessels, D.; Goosen, A.; Dallow, N.; Vessey, R.; Goldman, M. (British Journal of Clinical Pharmacology, 2006)