Link

Ashley, D.B., Tse, E.C., and Einstein, H.H. (1979). Advantages and limitations of adaptable tunnel design-construction methods. In: Proceedings of the 4th Rapid Excavation and Tunneling Conference, Atlanta, Georgia, 18-21 June 1979, v.2, pp. 989-1011. New York: Society of Mining Engineers of the American Institute of Mining, Metallurgical, and Petroleum Engineers, 1979. OneMine.org library