1. ASTM D6760 (2008). Standard Test Method for Integrity Testing of Concrete Deep Foundations by Ultrasonic Crosshole Testing.
2. Baker C.N. Drumright E.E. Briaud J-L. and Mensah F. (1993). Drilled Shafts for Bridge Foundations. FHWA Publication FHWA-RD-92-004 Federal Highway Administration Office of Engineering and Highway Operations McLean VA.
3. Camp W. M. Holley D.W. Canivan G.J. (2007). Crosshole Sonic Logging of South Carolina Drilled Shafts: A Five Year Summary. Deep Foundations American Society of Civil Engineers pp. 1-11.
4. Chang N. Nghiem H. (2008). Drilled Shaft Axial Capacity Due to Anomalies. Report No. FHWA-CFL/TD-08-008. Federal Highway Administration Colorado.