1. National Cooperative Highway Research Program (NCHRP) (1991).
2. Desai, C. S. and Wu, T. H. (1976), A General Function for Stress-Strain Curves, Proceedings of the 2nd International Conference on Numerical Methods in Geomechanics, American Society of Civil Engineers, Vol. 1, 306-318.
3. Wang, S.T. and Reese, L.C., (June 1993), COM624P, Laterally Loaded Pile Analysis for the Microcomputer, Version 2. 0, FHWA-SA-91-048, Springfield Va.