Hua, Li Cheng. „Study of Optimal Design of Parameters for Spade Punch Planter of Corn“.
agricultural engineering.eu
56, no. SH1 (Juli 30, 2001): 207–209. Zugegriffen April 9, 2025. http://195.37.233.21/landtechnik/article/view/2001-56-SH1-207-209.