1. The field performance of tractor draught control systems;Cowell;Journal of Agricultural Engineering Research,1967
2. Eine elektrohydraulische Zwei-Grössen-Tiefenregelung für grosse Schlepperanbaupflüge;Hesse;Grundlagen der Landtechnik,1972
3. Improvements to the kinematic design of tractor three point linkages;Herbert,1981
4. An investigation of the performance of a variable geometry three point linkage;Cowell,1984
5. A theory for the dynamic behaviour of mouldboard ploughs during penetration;Cowell;Journal of Agricultural Engineering Research,1976