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An introduction to multivariate statistical analysis
Anderson, Theodore W., (1958)
Multivariate statistical methods : a primer
Manly, Bryan F. J., (1994)
Manly, Bryan F. J., (1986)
Principal components analysis
Dunteman, George H., (2001)
Changing needle practices in community outreach and methadone treatment,
Wechsberg, Wendee M., (1994)