1. Soil dynamics in tillage and traction;Gill,1968
2. The performance of a rigid tine in relation to soil properties and speed;Stafford;J. agric. Engng Res.,1979
3. The calculation of passive pressure in two-dimensional soil failure;Hettiaratchi;J. agric. Engng Res.,1966
4. On yielding of soils;Roscoe;Géotechnique,1958
5. Critical state parameters of unsaturated soils;Potamias,1976