Niu, Ziru, Jianlei Li, Shuai Xin, Liangliang Zou, Yuhua Li, Jialin Hou, Ming Tu, and Ting Sun. 2020. “Geometrical Design of Variable Ratio Tooth Profile Based on Boolean Subtraction Operation and a Novel Modification Method”. International Journal of Agricultural and Biological Engineering 13 (5):125-33. https://ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/4884.