1. Hoek E. Practical rock engineering. Available from: 〈http://www.rockscience.com〉.
2. Rock slope stability on railway projects;Brawner;Am Railway Eng Assoc Bull,1976
3. Wyllie D. Rock slope inventory system. In: Proceedings of the FHWA rockfall mitigation seminary, FHWA Region 10, Portland, OR, 1987.
4. FHWA. Rock slopes: design, excavation, stabilization, FHWA-TS-89-045. Turner-Fairbank Highway Research Center, 1989.
5. Pierson LA, Davis SA, Van Vickle. Rockfall hazard rating system implementation manual. In: Federal highway administrations, report FHWA-OR-EG-90-01. Washington, DC: Federal Highway Administration, Department of Transportation; 1990.