Huang, Zhaofu, et al. “Analysis of Factors Affecting the Impurity Rate of Mechanically-Harvested Maize Grain in China”. International Journal of Agricultural and Biological Engineering, vol. 13, no. 5, Oct. 2020, pp. 17-22, https://www.ijabe.migration.pkpps06.publicknowledgeproject.org/index.php/ijabe/article/view/6038.