1. Consoli S, Moreno-Penrez JA, Darby-Dowman K, Mladenovic N (2010) Discrete particle swarm optimization for the minimum labelling steiner tree problem. Nat Comput 9(1):29–46
2. Coyle HM, Gibson GC (1970) Empirical damping constants for sands and clays. J Soil Mech Found Div ASCE (SM3) 96:949–965
3. Haykin S (1999) Neural Netwrok: a comprehensive foundation. Prentice Hall, New Jersey
4. Heerema EP (1979) Relationships between wall friction, displacement velocity and horizontal stress in clay and in sand for pile driveability analysis. Gr Eng 12(1):55–65
5. Isaacs DV (1931) Reinforced concrete pile formulae. Inst Aust Eng J 12:305–324