1. Barisone G, Pigorini B, Pelizza S. Umbrella arch method for tunnelling in difficult conditions-analysis of Italian cases. In: Proceedings of the fourth congress international association of engineering geology. New Delhi; 1982. p. 15–27.
2. Hoek E. Numerical modelling for shallow tunnels in weak rock. 2004. Available at: 〈www.rocscience.com/hoek/DiscussionPapers.asp〉.
3. Kim CY, Kim KY, Hong SW, Bae GJ, Shin HS. Interpretation of field measurements and numerical analyses on pipe umbrella method in weak ground tunneling. In: Proceedings of the 53rd geomechanics colloquy and EUROCK 2004 rock engineering theory and practice. Salzburg; 2004. p. 167–70.
4. Design and construction of mountain tunnels in Japan;Miura;Tunnel Underground Space Technol,2003
5. Gibbs PW, Lowrie J, Kieffer DS, McQueen L. M5 east—design of a shallow soft ground shotcrete motorway tunnel. In: Proceedings of the 28th ITA-AITES world tunneling congress. Sydney; March 2002.