1. Perennial experiments with tillage systems to improve the economy of cultivations for cereals;Patterson,1971
2. Applied Linear Programming;Driebeck,1969
3. Patterson, D. E. Private communication, January 1976
4. The annual cost of machinery calculated using actual cash flows;Audsley;J. agric. Engng Res.,1978
5. Matching tractor and implements for minimum cost cultivation;Audsley,1975