1. AASHTO. 1998. LRFD Bridge Design Specifications Foundation. 2nd ed. Washington, D.C.: American Association of State Highway and Transportation Officials.
2. Ang, A. H.-S., and W. H. X. Tang. 2007. Probability Concepts in Engineering Planning and Design: Emphasis on Application to Civil and Environmental Engineering. Hoboken, NJ: Wiley.
3. Reliability analysis for Serviceability Limit State of pile groups foundation
4. The Pile Efficiency Formula of the Uniform Building Code;Bolin H. W.;Building Standards Monthly,1941
5. Bowles J. E. 1995. Foundation Analysis and Design.