Parreira, A.B., Azevedo, R.F., and Zornberg, J.G. (1990). “Prediction of Stress_Strain and Strength Characteristics of the Red Clay and the Variegated Soil of São Paulo City using an Elasto-Plastic Model.” (in Portuguese), Proceedings of the Ninth Brazilian Conference on Soil Mechanics and Foundation Engineering, Salvador, Brazil, September, Vol. 2, pp. 45-52.