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 Mai 5, 2024. http://195.37.233.11/landtechnik/article/view/2001-56-SH1-207-209.