1. Jaeger JC, Cook NGW. Fundamentals of rock mechanics, 3rd ed. London: Chapman & Hall, 1979. p. 593.
2. Hoek E, Brown ET. Underground excavations in rock inst min metall. London: Stephen Austin and Sons, 1980. p. 527.
3. Pusch R. Rock mechanics on a geological base. Amsterdam: Elsevier, 1995. p. 498.
4. Hudson JA. Rock mechanics principles in engineering practice. CIRIA: Butterworths, 1989. p. 72.
5. ISRM. Suggested methods for determining the uniaxial compressive strength and deformability of rock materials. Int J Rock Mech Min Sci Geomech Abstr 1978;16:137–40.