Xing, X., S. Guangzhong, T. Kunyun, and R. Zhang. “Discrimination Methods of Water Inrush from Mine Floor Based on PCA-Fisher”. Journal of Mines, Metals and Fuels, vol. 66, no. 8, Oct. 2022, pp. 494-8, http://www.informaticsjournals.com/index.php/jmmf/article/view/31748.