References/Notes/Attributions:
Source
J.C. Gower and D.J. Hand (1996) Biplots. Chapman & Hall, Table 4.6.
Quoted as from:
R.H.G. Jongman, C.J.F. ter Braak and O.F.R. van Tongeren (1987) Data Analysis in Community and Landscape Ecology. PUDOC, Wageningen.
References
Venables, W. N. and Ripley, B. D. (2002) Modern Applied Statistics with S. Fourth edition. Springer.