1. AIJ (Architectural Institute of Japan). 2004. Recommendations for design of building foundations. Tokyo: AIJ.
2. ASTM. 2009. Standard test method for piles under static axial compressive load. ASTM D1143-87. West Conshohocken, PA: ASTM.
3. Boresi, A. 1965. Elasticity in engineering mechanics. Hoboken, NJ: Prentice Hall.
4. Briaud, J. L., S. Jeong, and R. Bush. 1991. “Group effect in the case of downdrag.” In Geotechnical Engineering Congress, Geotechnical Special Publication 27, edited by F. G. McLean, D. A. Campbell, and D. W. Harris, 505–518. Reston, VA: ASCE.
5. Broms, B. 1979. “Negative skin friction.” In Vol. 2 of Proc., 6th Asian Regional Conf. of Soil Mechanics and Foundation Engineering, 41–75. Singapore: Southeast Asian Society of Soil Engineers and Institute of Engineers.