Assessing essential oil composition in Cinnamomum cassia leaves from different regions of China using GC-MS and FTIR spectroscopy oleh Yan Huang, Yujie Liu, Huiping Tan, Yanrong Cheng, Kunyang Tao, Dingze Gu, Huaizu Cai, Chengjie Li, Kaiyi Guo, Cheng Wu, Hong Wu, Yanqun Li