Einstein, H.H., and Dowding, C.H. (1981). Shearing Resistance and Deformability of Rock Discontinuities. In Y.S. Touloukian, C.Y. Ho (eds.): Physical Properties of Rocks and Minerals, McGraw-Hill / CINDAS Data Series on Material Properties, Chapter 7, 177–219, 1981. ISBN: 978-0070650329