Penentuan Parameter Desain Roda Besi Bersirip melalui Pengukuran Tahanan Penetrasi Tanah di Sawah (Determining Parameters of Lug Wheels Design by Measurement of Soil Penetration Resistance in Paddy Field) - Rizaldi, Taufik (Faculty of Agricultural Technology, Universitas Gadjah Mada, Yogyakarta, Indonesia, 2015)