Yongguang, Hu, Liu Shengzhong, Wu Wenye, Wang Jizhang, and Shen Jianwen. 2015. “Optimal Flight Parameters of Unmanned Helicopter for Tea Plantation Frost Protection”. International Journal of Agricultural and Biological Engineering 8 (5):50-57. https://doi.org/10.25165/ijabe.v8i5.1655.