W. Jinwu, T. Guixiang, L. Yongjun, P. Zhenwei, and Z. Chunfeng, “Field experimental study on pullout forces of rice seedlings and barnyard grasses for mechanical weed control in paddy field”, Int J Agric & Biol Eng, vol. 7, no. 6, pp. 1–7, Dec. 2014.