Link

Einstein, H.H., Steiner, W., and Baecher, G.B. (1979). Assessment of empirical design methods for tunnels in rock. In: Proceedings of the 4th Rapid Excavation and Tunneling Conference, Atlanta, Georgia, 18-21 June 1979, v.1, pp. 683-706. New York: Society of Mining Engineers of the American Institute of Mining, Metallurgical, and Petroleum Engineers, 1979. OneMine.org library