Efficacy and safety of Qi-Jing Hui-Xin Decoction in the treatment of coronary microvascular angina: study protocol for a randomized, controlled, multi-center clinical trial. - Sun, Yuanlong; Huang, Chengxin; Huo, Li; Li, Ying; Chen, Jun; Zhang, Zixiu; Jia, Meijun; Jiang, Meixian; Ruan, Xiaofen (Trials, 2021)