Prediction of gas and coal spontaneous combustion coexisting disaster through the chaotic characteristic analysis of gas indexes in goaf gas extraction. - Song, Yawei; Yang, Shengqiang; Hu, Xincheng; Song, Wanxin; Sang, Naiwen; Cai, Jiawen; Xu, Qin (Process Safety & Environmental Protection: Transactions of the Institution of Chemical Engineers Part B, 2019)