The IBV Valve trial: a multicenter, randomized, double-blind trial of endobronchial therapy for severe emphysema. - Wood DE; Nader DA; Springmeyer SC; Elstad MR; Coxson HO; Chan A; Rai NS; Mularski RA; Cooper CB; Wise RA; Jones PW; Mehta AC; et al. (Journal of bronchology & interventional pulmonology, 2014)