1. AFENA Users Manual, Geotechnical Research Centre;Carter,1990
2. The effect of increasing strength with depth on the bearing capacity of clays;Davis;Géotechnique,1973
3. Direct solution of plasticity problems in soils by the method of characteristics;Houlsby;Proc. 4th ICONMIG,1982
4. Calculation of stresses on shallow penetrometers and footings;Houlsby,1983
5. Numerical simulation of pipe penetration in non-homogeneous soil;Hu,1995