1. Aitchison, G.D. and Donald, I.B.: Some preliminary studies of unsaturated soils. (b) Effective stresses in unsaturated soils, Proc. 2nd Austr.–N. Zealand Conf. Soil Mech. and Found. Engng., Christchurch, 1956, 192–199.
2. Bishop, A.W. and Donald, I.B: The experimental study of partly saturated soils in the triaxial apparatus. Proc. 5th. Int. Conf. Soil Mech. and Found. Engng., 1961, 1, 13–21.
3. Bishop, A.W. and Blight, G.E.: Some aspects of effective stress in saturated and partly saturated soils. Géotechnique, 13 (1963), 177–197.
4. Burland, J.B.: Some aspects of the mechanical behaviour of partially saturated soils. Moisture Equilibria and Moisture Changes Beneath Covered Areas, Butterworths, Sydney 1965, 270–278.
5. Coleman, J.D.: Stress strain relations for partly saturated soil. Géotechnique, 12 (1962), 348–350.