1. Foundation design and construction;Tomlinson,2001
2. History of pile foundation engineering;Ulitskii;Soil Mech Found Eng,1995
3. DIN 4014. Bored piles: construction procedure, design and bearing behaviour. Berlin: German code; 1990.
4. Eurocode 7: Geotechnical design – part 1: general rules, (EN 1997–1). Brussels: CEN European Committee for standardization.
5. Subsoil – verification of the safety of earthworks and foundations;DIN 1054,1990