Diagnostic value of impulse oscillometry in chronic obstructive pulmonary disease: a multicentre, retrospective, observational study oleh Hui Zhou, Hao Wang, Lin Liu, Lei Chen, Tao Wang, Yongchun Shen, Lijuan Gao, Dan Xu, Fu-Qiang Wen, Yanqiu Wu, Shuguang Xiong, Rong Qiu, Huizhuo Jia, Jiangyue Qin