Abramson, L.W., Lee, T.S., Sharma, S., Boyce, G.M. (2002) Slope Stability and Stabilization Methods, 2nd ed. John Wiley & Sons.Hoek, E. & Bray, J.W. (1981) Rock Slope Engineering (3rd Ed.). The Institution of Mining and Metallurgy, London.Hoek, E. (2007) Rock Engineering. Course notes by Evert Hoek. www.rocscience, 313 p..Fernandes, M.M. (2011) Mecânica dos Solos. Introdução à Engenharia Geotécnica. FEUP, Porto, 592 p.Das, B. M. (2010) Principles of Geotechnical Engineering, 7th ed., Cengage Learning, 704 p.Hoek E. and Brown E.T. (1980) Underground Excavations in Rock. The Institution of Mining and Metallurgy, London, 527 pages: