Hydrogen/oxygen therapy for the treatment of an acute exacerbation of chronic obstructive pulmonary disease: results of a multicenter, randomized, double-blind, parallel-group controlled trial. - Zheng, Ze-Guang; Sun, Wu-Zhuang; Hu, Jie-Ying; Jie, Zhi-Jun; Xu, Jin-Fu; Cao, Jie; Song, Yuan-Lin; Wang, Chang-Hui; Wang, Jing; Zhao, Hui; Guo, Zhong-Liang; Zhong, Nan-Shan (Respiratory Research, 2021)