1. Perennial experiments with tillage systems to improve the economy of cultivations for cereals. 3rd year 1973/1974 experiments;Patterson,1974
2. Perennial experiments with tillage systems to improve the economy of cultivations for cereals. 4th year 1974/1975 experiments;Patterson,1975
3. Perennial experiments with tillage systems to improve the economy of cultivations for cereals. 5th year 1975/1976 experiments;Patterson,1976
4. Perennial experiments with tillage systems to improve the economy of cultivations for cereals. 6th year 1976/1977 experiments;Patterson,1977
5. Fast-running rotary cultivators and slow-running rotary diggers. Investigations on individual tools;Söhne;Trans. N.I.A.E. No. 11, Grundl. Landtech.,1959