Friendly, M. (1991), SAS System for Statistical Graphics, SAS Series in Statistical Applications, Cary, NC: SAS Institute Inc.
Gabriel, K. R. (1971), “The Biplot Graphical Display of Matrices with Applications to Principal Component Analysis,” Biometrika, 58, 453–467.
Golub, G. H. and Van Loan, C. F. (1989), Matrix Computations, 2nd Edition, Baltimore: Johns Hopkins University Press.
Gower, J. C. and Hand, D. J. (1996), Biplots, London: Chapman & Hall.
Jackson, J. E. (1991), A User’s Guide to Principal Components, New York: John Wiley & Sons.