The Lithium Abundances from the Large Sky Area Multi-object Fiber Spectroscopic Telescope Medium-resolution Survey. I. The Method. - Gao, Qi; Shi, Jian-Rong; Yan, Hong-Liang; Li, Chun-Qian; Chen, Tian-Yi; Zhang, Jing-Hua; Liu, Shuai; Yan, Tai-Sheng; Xie, Xiao-Jin; Ding, Ming-Yi; Zhang, Yong; Hou, Yong-Hui (Astrophysical Journal, 2021)